My laptop has been working fine since the fresh install of 22.04.
Today, however, I noticed a question mark instead of the connection icon
while trying to connect to my wired router. First step was to swap out
the 50 foot cat5 cable, same thing. Then, swap out for another shorter
one I use for situations like now when I need to get back on the
desktop. Still have the question mark. As you can see, my connection
is fine from the desktop and both are using the same router.

Trying to troubleshoot, first thing I did was to turn off "connectivity
checking" under privacy. That gives the solid connection icon now, but
still no apparent connectivity.

I've tried to restart network manager and get a message about failing to
restart, but that was before rebooting. Once rebooted, no difference,
still unable to connect.

Any suggestions welcome. Everything had been working fine until this
morning.

Thanks in advance.

On 11 Oct 2022 10:45:53 -0400 wAYNE <none@nowhere.net> wrote:

> Any suggestions welcome. Everything had been working fine until this
> morning.

Post the output of

ip a
resolvectl
cat /etc/resolv.conf

When the connection is established and the question mark is there.

On 10/11/22 10:47 AM, Marco Moock wrote:
> On 11 Oct 2022 10:45:53 -0400 wAYNE <none@nowhere.net> wrote:
>
>> Any suggestions welcome. Everything had been working fine until this
>> morning.
>
> Post the output of
>
> ip a
> resolvectl
> cat /etc/resolv.conf
>
> When the connection is established and the question mark is there.
>

ip a

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN
group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: enp9s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel
state UP group default qlen 1000
link/ether 00:23:ae:31:df:70 brd ff:ff:ff:ff:ff:ff
inet 192.168.1.224/24 brd 192.168.1.255 scope global dynamic
noprefixroute enp9s0
valid_lft 563sec preferred_lft 563sec
inet6 fe80::db86:de8c:8266:76/64 scope link noprefixroute
valid_lft forever preferred_lft forever
3: wlp12s0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group
default qlen 1000
link/ether 0c:60:76:66:f6:c4 brd ff:ff:ff:ff:ff:ff

resolvectl

Protocols: -LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
resolv.conf mode: stub

Link 2 (enp9s0)
Current Scopes: DNS
Protocols: +DefaultRoute +LLMNR -mDNS -DNSOverTLS
DNSSEC=no/unsupported
Current DNS Server: 192.168.1.1
DNS Servers: 192.168.1.1
DNS Domain: fios-router.home

Link 3 (wlp12s0)
Current Scopes: none
Protocols: -DefaultRoute +LLMNR -mDNS -DNSOverTLS
DNSSEC=no/unsupported

cat /etc/resolv.conf

# This is /run/systemd/resolve/stub-resolv.conf managed by
man:systemd-resolved(8).
# Do not edit.
# # This file might be symlinked as /etc/resolv.conf. If you're looking at
# /etc/resolv.conf and seeing this text, you have followed the symlink.
# # This is a dynamic resolv.conf file for connecting local clients to the
# internal DNS stub resolver of systemd-resolved. This file lists all
# configured search domains.
# # Run "resolvectl status" to see details about the uplink DNS servers
# currently in use.
# # Third party programs should typically not access this file directly,
but only
# through the symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a
# different way, replace this symlink by a static file or a different
symlink.
# # See man:systemd-resolved.service(8) for details about the supported
modes of
# operation for /etc/resolv.conf.

nameserver 127.0.0.53
options edns0 trust-ad
search fios-router.home

On 10/11/22 11:14 AM, wAYNE wrote:
> On 10/11/22 10:47 AM, Marco Moock wrote:
>> On 11 Oct 2022 10:45:53 -0400 wAYNE <none@nowhere.net> wrote:
>>
>>> Any suggestions welcome.  Everything had been working fine until this
>>> morning.
>>
>> Post the output of
>>
>> ip a
>> resolvectl
>> cat /etc/resolv.conf
>>
>> When the connection is established and the question mark is there.
>>
>
>
> ip a
>
> 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN
> group default qlen 1000
>     link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
>     inet 127.0.0.1/8 scope host lo
>        valid_lft forever preferred_lft forever
>     inet6 ::1/128 scope host
>        valid_lft forever preferred_lft forever
> 2: enp9s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel
> state UP group default qlen 1000
>     link/ether 00:23:ae:31:df:70 brd ff:ff:ff:ff:ff:ff
>     inet 192.168.1.224/24 brd 192.168.1.255 scope global dynamic
> noprefixroute enp9s0
>        valid_lft 563sec preferred_lft 563sec
>     inet6 fe80::db86:de8c:8266:76/64 scope link noprefixroute
>        valid_lft forever preferred_lft forever
> 3: wlp12s0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group
> default qlen 1000
>     link/ether 0c:60:76:66:f6:c4 brd ff:ff:ff:ff:ff:ff
>
>
>
>
>
> resolvectl
>
>            Protocols: -LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
> resolv.conf mode: stub
>
> Link 2 (enp9s0)
>     Current Scopes: DNS
>          Protocols: +DefaultRoute +LLMNR -mDNS -DNSOverTLS
> DNSSEC=no/unsupported
> Current DNS Server: 192.168.1.1
>        DNS Servers: 192.168.1.1
>         DNS Domain: fios-router.home
>
> Link 3 (wlp12s0)
> Current Scopes: none
>      Protocols: -DefaultRoute +LLMNR -mDNS -DNSOverTLS
> DNSSEC=no/unsupported
>
>
>
>
> cat /etc/resolv.conf
>
>
> # This is /run/systemd/resolve/stub-resolv.conf managed by
> man:systemd-resolved(8).
> # Do not edit.
> #
> # This file might be symlinked as /etc/resolv.conf. If you're looking at
> # /etc/resolv.conf and seeing this text, you have followed the symlink.
> #
> # This is a dynamic resolv.conf file for connecting local clients to the
> # internal DNS stub resolver of systemd-resolved. This file lists all
> # configured search domains.
> #
> # Run "resolvectl status" to see details about the uplink DNS servers
> # currently in use.
> #
> # Third party programs should typically not access this file directly,
> but only
> # through the symlink at /etc/resolv.conf. To manage man:resolv.conf(5)
> in a
> # different way, replace this symlink by a static file or a different
> symlink.
> #
> # See man:systemd-resolved.service(8) for details about the supported
> modes of
> # operation for /etc/resolv.conf.
>
> nameserver 127.0.0.53
> options edns0 trust-ad
> search fios-router.home
>

Ok, so I'm back on the laptop and typing from it. I noticed that the
same symptoms were happening on here when I booted into Win 10. So, I
tried something I haven't done in years with the laptop, enabled WiFi.
Once I did that, and also enabled my Fios WiFi router, I was able to
connect fully.... but now it seems that I've lost my wired desktop
connection.
I haven't used WiFi for years for PC to router connection, so don't
recall if I can connect to the Fios router simultaneously with both WiFi
and wired connections, but I should be able to! Any thoughts on that
welcome. It's probably something with the router settings....
As far as the laptop, since it only connects by WiFi now on both Win and
Ubuntu and not wired, I am suspecting an issue with the wired jack or
something on the motherboard(?). Not a happy camper about that. I
prefer my wired connections over wireless.

Am 11.10.2022 um 12:09:13 Uhr schrieb wAYNE:

> and also enabled my Fios WiFi router, I was able to
> connect fully.

Post the outputs again when connected to WiFi.
You don't have IPv6 (maybe you can enable that in the router).

Ok, managed to get everything working again although not quite to my
satisfaction.

Apparently, I had to go into the router and "unblock" my desktop, since
it uses a wired, and the laptop uses the WiFi. Once that was done, now
both PCs can simultaneously connect.

I'm not happy about having to enable WiFi on the laptop to get
connectivity. Any thought on why the wired no longer works would be
welcome. As I mentioned, it seems to not work wired on either Win or
Ubuntu, whichever I boot into. Switching out cat5 cables did not
remedy. Could it be a connector, motherboard, or bios issue?

A separate question relating to Wifi frequency. I'm on the old Dell
Inspiron 1545 laptop. In the Fios router, it seems to have both 2.4 Ghz
and 5 Ghz. I set up for 2.4. Should I stick with that, or try the 5
Ghz connection and, if so, what's the advantage if any? As I said, I
haven't used or configured WiFi in years.

Thanks in advance.

On 10/11/22 12:26 PM, Marco Moock wrote:
> Am 11.10.2022 um 12:09:13 Uhr schrieb wAYNE:
>
>> and also enabled my Fios WiFi router, I was able to
>> connect fully.
>
> Post the outputs again when connected to WiFi.
> You don't have IPv6 (maybe you can enable that in the router).
>

ip a

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN
group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: enp9s0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc fq_codel
state DOWN group default qlen 1000
link/ether 00:23:ae:31:df:70 brd ff:ff:ff:ff:ff:ff
3: wlp12s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel
state UP group default qlen 1000
link/ether 0c:60:76:66:f6:c4 brd ff:ff:ff:ff:ff:ff
inet 192.168.1.151/24 brd 192.168.1.255 scope global dynamic
noprefixroute wlp12s0
valid_lft 85017sec preferred_lft 85017sec
inet6 fe80::99c:a3a7:1955:7435/64 scope link noprefixroute
valid_lft forever preferred_lft forever

resolvectl

Global
Protocols: -LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
resolv.conf mode: stub

Link 2 (enp9s0)
Current Scopes: none
Protocols: -DefaultRoute +LLMNR -mDNS -DNSOverTLS
DNSSEC=no/unsupported

Link 3 (wlp12s0)
Current Scopes: DNS
Protocols: +DefaultRoute +LLMNR -mDNS -DNSOverTLS
DNSSEC=no/unsupported
Current DNS Server: 192.168.1.1
DNS Servers: 192.168.1.1
DNS Domain: fios-router.home

cat /etc/resolv.conf

# This is /run/systemd/resolve/stub-resolv.conf managed by
man:systemd-resolved(8).
# Do not edit.
# # This file might be symlinked as /etc/resolv.conf. If you're looking at
# /etc/resolv.conf and seeing this text, you have followed the symlink.
# # This is a dynamic resolv.conf file for connecting local clients to the
# internal DNS stub resolver of systemd-resolved. This file lists all
# configured search domains.
# # Run "resolvectl status" to see details about the uplink DNS servers
# currently in use.
# # Third party programs should typically not access this file directly,
but only
# through the symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a
# different way, replace this symlink by a static file or a different
symlink.
# # See man:systemd-resolved.service(8) for details about the supported
modes of
# operation for /etc/resolv.conf.

nameserver 127.0.0.53
options edns0 trust-ad
search fios-router.home

You also get IPv4 and DNS. Please try ping google.de with Ethernet and
WIFi.

On Tue, 11 Oct 2022 12:29:13 -0400, wAYNE wrote:

> Ok, managed to get everything working again although not quite to my
> satisfaction.
>
> Apparently, I had to go into the router and "unblock" my desktop, since
> it uses a wired, and the laptop uses the WiFi. Once that was done, now
> both PCs can simultaneously connect.
>
> I'm not happy about having to enable WiFi on the laptop to get
> connectivity. Any thought on why the wired no longer works would be
> welcome. As I mentioned, it seems to not work wired on either Win or
> Ubuntu, whichever I boot into. Switching out cat5 cables did not
> remedy. Could it be a connector, motherboard, or bios issue?
>
> A separate question relating to Wifi frequency. I'm on the old Dell
> Inspiron 1545 laptop. In the Fios router, it seems to have both 2.4 Ghz
> and 5 Ghz. I set up for 2.4. Should I stick with that, or try the 5
> Ghz connection and, if so, what's the advantage if any? As I said, I
> haven't used or configured WiFi in years.
>
> Thanks in advance.

% Ghz will give much better thru put, I would use that if your laptop is
close to your router. % Ghz gets progressively weak the more walls it
must go thru.

As far as your wired connection gos, di you try a different network port
on your router? You also may want to check the wired port speed settings
on your router for the port that is giving you trouble. I always hard
code the port speed and duplex. Auto-negotiate is kinda of picky that is
why I had code.

--
Pull my finger

On 10/11/22 4:57 PM, Killadebug wrote:
> On Tue, 11 Oct 2022 12:29:13 -0400, wAYNE wrote:
>
>> Ok, managed to get everything working again although not quite to my
>> satisfaction.
>>
>> Apparently, I had to go into the router and "unblock" my desktop, since
>> it uses a wired, and the laptop uses the WiFi. Once that was done, now
>> both PCs can simultaneously connect.
>>
>> I'm not happy about having to enable WiFi on the laptop to get
>> connectivity. Any thought on why the wired no longer works would be
>> welcome. As I mentioned, it seems to not work wired on either Win or
>> Ubuntu, whichever I boot into. Switching out cat5 cables did not
>> remedy. Could it be a connector, motherboard, or bios issue?
>>
>> A separate question relating to Wifi frequency. I'm on the old Dell
>> Inspiron 1545 laptop. In the Fios router, it seems to have both 2.4 Ghz
>> and 5 Ghz. I set up for 2.4. Should I stick with that, or try the 5
>> Ghz connection and, if so, what's the advantage if any? As I said, I
>> haven't used or configured WiFi in years.
>>
>> Thanks in advance.
>
> % Ghz will give much better thru put, I would use that if your laptop is
> close to your router. % Ghz gets progressively weak the more walls it
> must go thru.
>
> As far as your wired connection gos, di you try a different network port
> on your router? You also may want to check the wired port speed settings
> on your router for the port that is giving you trouble. I always hard
> code the port speed and duplex. Auto-negotiate is kinda of picky that is
> why I had code.
>
>
>

Yes, I did try different router ports but no difference. I'm now
thinking that this is the charger board in the laptop as it contains
the power jack, USB port and ethernet port. It is a small board that
can be replaced and I have a replacement on the way. I just got
finished swapping out the defunct motherboard and it's possible that the
charger board is causing trouble.

On 10/11/2022 7:40 PM, wAYNE wrote:
> On 10/11/22 4:57 PM, Killadebug wrote:
>> On Tue, 11 Oct 2022 12:29:13 -0400, wAYNE wrote:
>>
>>> Ok, managed to get everything working again although not quite to my
>>> satisfaction.
>>>
>>> Apparently, I had to go into the router and "unblock" my desktop, since
>>> it uses a wired, and the laptop uses the WiFi.  Once that was done, now
>>> both PCs can simultaneously connect.
>>>
>>> I'm not happy about having to enable WiFi on the laptop to get
>>> connectivity.  Any thought on why the wired no longer works would be
>>> welcome.  As I mentioned, it seems to not work wired on either Win or
>>> Ubuntu, whichever I boot into.  Switching out cat5 cables did not
>>> remedy.  Could it be a connector, motherboard, or bios issue?
>>>
>>> A separate question relating to Wifi frequency.  I'm on the old Dell
>>> Inspiron 1545 laptop.  In the Fios router, it seems to have both 2.4 Ghz
>>> and 5 Ghz.  I set up for 2.4.  Should I stick with that, or try the 5
>>> Ghz connection and, if so, what's the advantage if any?  As I said, I
>>> haven't used or configured WiFi in years.
>>>
>>> Thanks in advance.
>>
>> % Ghz will give much better thru put, I would use that if your laptop is
>> close to your router. % Ghz gets progressively weak the more walls it
>> must go thru.
>>
>> As far as your wired connection gos, di you try a different network port
>> on your router? You also may want to check the wired port speed settings
>> on your router for the port that is giving you trouble. I always hard
>> code the port speed and duplex. Auto-negotiate is kinda of picky that is
>> why I had code.
>>
>>
>>
>
> Yes, I did try different router ports but no difference.  I'm now thinking that this is the charger board in the laptop as it contains the power jack, USB port and ethernet port.  It is a small board that can be replaced and I have a replacement on the way.  I just got finished swapping out the defunct motherboard and it's possible that the charger board is causing trouble.

That's one weird board. The Ethernet port connector looks
like a trouble-maker. Like the wires are SMT and underneath
the connector body.

https://www.dcxpower.com/dell-inspiron-1545-1546-pp41l-484aq03011021c11c21-484aq13csc-484aq200sb-484aq230sb-dr1-0853012sc-dc-power-jack-socket-connector-vga-rj45-lan-usb-port-in-charging-board-p-194.html

Paul

On 10/12/22 9:22 AM, Paul wrote:
> On 10/11/2022 7:40 PM, wAYNE wrote:
>> On 10/11/22 4:57 PM, Killadebug wrote:
>>> On Tue, 11 Oct 2022 12:29:13 -0400, wAYNE wrote:
>>>
>>>> Ok, managed to get everything working again although not quite to my
>>>> satisfaction.
>>>>
>>>> Apparently, I had to go into the router and "unblock" my desktop, since
>>>> it uses a wired, and the laptop uses the WiFi.  Once that was done, now
>>>> both PCs can simultaneously connect.
>>>>
>>>> I'm not happy about having to enable WiFi on the laptop to get
>>>> connectivity.  Any thought on why the wired no longer works would be
>>>> welcome.  As I mentioned, it seems to not work wired on either Win or
>>>> Ubuntu, whichever I boot into.  Switching out cat5 cables did not
>>>> remedy.  Could it be a connector, motherboard, or bios issue?
>>>>
>>>> A separate question relating to Wifi frequency.  I'm on the old Dell
>>>> Inspiron 1545 laptop.  In the Fios router, it seems to have both 2.4
>>>> Ghz
>>>> and 5 Ghz.  I set up for 2.4.  Should I stick with that, or try the 5
>>>> Ghz connection and, if so, what's the advantage if any?  As I said, I
>>>> haven't used or configured WiFi in years.
>>>>
>>>> Thanks in advance.
>>>
>>> % Ghz will give much better thru put, I would use that if your laptop is
>>> close to your router. % Ghz gets progressively weak the more walls it
>>> must go thru.
>>>
>>> As far as your wired connection gos, di you try a different network port
>>> on your router? You also may want to check the wired port speed settings
>>> on your router for the port that is giving you trouble. I always hard
>>> code the port speed and duplex. Auto-negotiate is kinda of picky that is
>>> why I had code.
>>>
>>>
>>>
>>
>> Yes, I did try different router ports but no difference.  I'm now
>> thinking that this is the charger board in the laptop as it contains
>> the power jack, USB port and ethernet port.  It is a small board that
>> can be replaced and I have a replacement on the way.  I just got
>> finished swapping out the defunct motherboard and it's possible that
>> the charger board is causing trouble.
>
> That's one weird board. The Ethernet port connector looks
> like a trouble-maker. Like the wires are SMT and underneath
> the connector body.
>
> https://www.dcxpower.com/dell-inspiron-1545-1546-pp41l-484aq03011021c11c21-484aq13csc-484aq200sb-484aq230sb-dr1-0853012sc-dc-power-jack-socket-connector-vga-rj45-lan-usb-port-in-charging-board-p-194.html
>
>    Paul
>
I've been keeping at least one 1545 going for about ten years now. It's
cheaper than buying new. Although I've replaced motherboards twice,
this is the first time since I've owned one that I had trouble with the
port. I found out today that I could have used an ethernet to USB
adapter, which I didn't know about, but the charger board is already on
the way. Of course, I'll have to repeat the disassembly process like
I'm changing out the motherboard, but, at this point, I'm used to it.
The most annoying thing about the 1545 was the CMOS battery replacement.
Just to change it required almost complete disassembly, but I remedied
that by using a small dremel tool to cut a square into the casing so
that, when the CPU/ memory cover is removed, the battery can be changed
out as well if needed. There is no visible modification once the CPU
cover is back in place and infinitely much easier battery changes! Of
course, the modification has to be done while the motherboard is out of
the unit; otherwise surely the metal shavings would short something.

On 10/13/2022 2:39 PM, wAYNE wrote:
> On 10/12/22 9:22 AM, Paul wrote:
>> On 10/11/2022 7:40 PM, wAYNE wrote:
>>> On 10/11/22 4:57 PM, Killadebug wrote:
>>>> On Tue, 11 Oct 2022 12:29:13 -0400, wAYNE wrote:
>>>>
>>>>> Ok, managed to get everything working again although not quite to my
>>>>> satisfaction.
>>>>>
>>>>> Apparently, I had to go into the router and "unblock" my desktop, since
>>>>> it uses a wired, and the laptop uses the WiFi.  Once that was done, now
>>>>> both PCs can simultaneously connect.
>>>>>
>>>>> I'm not happy about having to enable WiFi on the laptop to get
>>>>> connectivity.  Any thought on why the wired no longer works would be
>>>>> welcome.  As I mentioned, it seems to not work wired on either Win or
>>>>> Ubuntu, whichever I boot into.  Switching out cat5 cables did not
>>>>> remedy.  Could it be a connector, motherboard, or bios issue?
>>>>>
>>>>> A separate question relating to Wifi frequency.  I'm on the old Dell
>>>>> Inspiron 1545 laptop.  In the Fios router, it seems to have both 2.4 Ghz
>>>>> and 5 Ghz.  I set up for 2.4.  Should I stick with that, or try the 5
>>>>> Ghz connection and, if so, what's the advantage if any?  As I said, I
>>>>> haven't used or configured WiFi in years.
>>>>>
>>>>> Thanks in advance.
>>>>
>>>> % Ghz will give much better thru put, I would use that if your laptop is
>>>> close to your router. % Ghz gets progressively weak the more walls it
>>>> must go thru.
>>>>
>>>> As far as your wired connection gos, di you try a different network port
>>>> on your router? You also may want to check the wired port speed settings
>>>> on your router for the port that is giving you trouble. I always hard
>>>> code the port speed and duplex. Auto-negotiate is kinda of picky that is
>>>> why I had code.
>>>>
>>>>
>>>>
>>>
>>> Yes, I did try different router ports but no difference.  I'm now thinking that this is the charger board in the laptop as it contains the power jack, USB port and ethernet port.  It is a small board that can be replaced and I have a replacement on the way.  I just got finished swapping out the defunct motherboard and it's possible that the charger board is causing trouble.
>>
>> That's one weird board. The Ethernet port connector looks
>> like a trouble-maker. Like the wires are SMT and underneath
>> the connector body.
>>
>> https://www.dcxpower.com/dell-inspiron-1545-1546-pp41l-484aq03011021c11c21-484aq13csc-484aq200sb-484aq230sb-dr1-0853012sc-dc-power-jack-socket-connector-vga-rj45-lan-usb-port-in-charging-board-p-194.html
>>
>>     Paul
>>
>
> I've been keeping at least one 1545 going for about ten years now.  It's cheaper than buying new.  Although I've replaced motherboards twice, this is the first time since I've owned one that I had trouble with the port.  I found out today that I could have used an ethernet to USB adapter, which I didn't know about, but the charger board is already on the way.  Of course, I'll have to repeat the disassembly process like I'm changing out the motherboard, but, at this point, I'm used to it.
>
> The most annoying thing about the 1545 was the CMOS battery replacement.  Just to change it required almost complete disassembly, but I remedied that by using a small dremel tool to cut a square into the casing so that, when the CPU/ memory cover is removed, the battery can be changed out as well if needed. There is no visible modification once the CPU cover is back in place and infinitely much easier battery changes!  Of course, the modification has to be done while the motherboard is out of the unit; otherwise surely the metal shavings would short something.

There is a way to test Ethernet wiring.

One of the Marvell NIC chips, has the ability to check the
continuity of Ethernet wires and transformers. (The keyword is
VCT in the documentation...)

On this page, in the lower left corner, is a download button
for the Marvell whitepaper on Virtual Cable Tester.

https://www.teklib.com/library/vct-marvell-virtual-cable-tester-technology-for-gigabit-networks-white-paper/

Name: Virtual_Cable_Tester_Marvell_WP.pdf
Size: 743522 bytes (726 KiB)
SHA256: 4CA96A44A49ED3EE54055F275DCB89BFEB01299338ABFF1C3B9FE5420EFDE689

To use the tester, you do the following:

1) PC with particular Marvel VCT NIC is powered and conducts the test.
2) Run Ethernet cable to a second piece of equipment.
3) The second piece of equipment is *unpowered*. This prevents
HeartBeat activity from screwing up the pulses.
4) Cable has a max of four pairs (i.e. GbE). The status of
the pairs can be Short, Open, Good (characteristic termination).

Marvell ----\||/--------------------\||/----+-------+ Conceptual
VCT /||\ /||\ | Foreign diagram of
1of4 pair \||/ \||/ Rterm XCVR method
----/||\--------------------/||\----+-------+

I only own one of those chips, and the motherboard is dead,
so the chip is now an orphan. But what was pretty funny in
my mind, is when the motherboard was new, one of the first
features I tested was VCT... and the Ethernet connector had
dirt on one pin, and one pair measured open at zero feet :-)
So it did not pass the test, on the very first usage.
Just inserting and removing the connector five times,
cleaned off the manufacturing residue. Then it passed.

But at least it does show, that it is possible to implement
Time Domain Reflectometry inside a NIC, for testing that
a wire is broke somewhere. It can show you, for example,
that a wire is broken inside a 100 foot long Ethernet cable.
The distance to the trouble, is only a rough estimate.
It's not as good as a real TDR instrument with 35pS
rise time tunnel diode stimulus.

After giving up on Ethernet, Marvell today does seem to be
interested in NICs again. But perhaps it will be some
time before we see a product with the Marvell name on
the box. (A couple years ago, there were boxes with
Marvell printed on them, you open the box, and RealTek
was inside...) Whether they will have VCT, is another matter.

Paul