Debian 12 MESA ethernet with wifi configuration

Yes, that's what I did. Sorry if I wasn't clear enough.

Original issue was that I could get both networks up and working:

1. ethernet connection to MESA baord with static IP set to 10.10.10.2
2. wifi connection to LAN

But whenever I tried connecting them concurrently, my connection to LAN no longer worked.
The problem with LAN turned out to be a router configuration issue.

There's still an issue with the GUI NetworkManagemer Applet. When I configure the Ethernet connection with static IP address via the GUI, it connects and then disconnects spuriously.

 When I configure the same connection  via the /etc/network/interfaces file, the connection works without issues. I'm fine with this; I'm just posting here for posterity.

Thanks
 

Make sure you have also set the network connection for your ethernet port to static. Even though I had an IP set in the configs, it was still set for DHCP, which caused a disconnect issue similar to what you described.