Ubuntu 22.04 network error

Technical Help
1

When I connect wi-fi, wired connection says Ethernet connection is established, but when I disconnect the wi-fi, in the settings, Ethernet connection is connected but internet connection is not work.
ex) ping facebook.com // name resolution error

I think it is name server problem, so I also modified the name server.but the problem is still valid. There was no problem when using 18.04, but after changing to 22.04 it looks like this. I’ve reinstalled it about 3 times now.

is it a bug / issue or didn’t i have enough coffee?
best regards from korea

2

You can see if a IP address is assigned with:

$ ip address show

And you can see the links and routing with:

$ ip link
and
$ ip route

To test the network you can ping a IP address directly example (googles DNS):

   $ ping -c 3 8.8.8.8

And you can see the name resolution in:

   $ cat /etc/resolv.conf

If ping works, it is likely the network configuration is no longer working.
It could be old settings or other issues. (some formats have changed).

  $ cat /etc/netplan/*

For example in the netplan ‘gateway4’ is deprecated and you should use ‘routes’ now.
For that specific example there is a write up:
netplan generate: `gateway4` has been deprecated, use default routes instead - Unix & Linux Stack Exchange

Well that should give you a start of a few things to look for.

Mark