@neil @WiteWulf Depending on the system specifics, the first option recommended here might not work.
I'm on Ubuntu 25.10, and by default my wireless network (Gnosis) has a higher autoconnect-priority value:
❯ nmcli -f name,autoconnect,autoconnect-priority c
NAME AUTOCONNECT AUTOCONNECT-PRIORITY
Wired connection 1 yes -999
Gnosis yes 0
lo no 0
Looking at the route table, though, you'll see that we're doing the "right" thing and prioritizing the wired interface by setting a higher metric (600) on the wireless interface (wlp63s0).
❯ ip route
default via 192.168.1.1 dev enp11s0 proto dhcp src 192.168.1.168 metric 100
default via 192.168.1.1 dev wlp63s0 proto dhcp src 192.168.1.167 metric 600
192.168.1.0/24 dev enp11s0 proto kernel scope link src 192.168.1.168 metric 100
192.168.1.0/24 dev wlp63s0 proto kernel scope link src 192.168.1.167 metric 600
This is the default behavior for Debian, I think.