Screwy network

[MR ZenWiz]

I run Xubuntu 21.10 on my desktop (and 20.04 on all my other
computers). It has wired and wireless connections built into the mobo
(ASUS TUF270X).

This morning, the wired connection didn't work at all, so I enabled
the wifi.  That works, partly.  I can reach the internet and am
writing this in Chrome Gmail through the wifi.

However, for all my local machines that are also on the same router,
mostly wifi, I cannot ping them from the desktop and they cannot ping
the desktop remotely.

On the other machines, I can reach the other connections, including
the internet, but not the desktop.

I rebooted the desktop (radical Windows solution, I know), but that
made no difference except to confirm that the wire to the router is
failing.  I need to replace that wire anyway, but it has been working
for the most part until now (again), with only intermittent failures
that didn't cripple the wifi or impact them in any other way.

Also, I'm showing three icons for the network on the panel - two in
the notification app and one of its own.  Never seen that before.

I'm totally baffled by this.  Where do I look to see if I can find out
what the heck is going on?

Thanks in advance.

Mark