I tried to set up wireguard using the "official" instructions which look pretty straightforward. Still, after completing them, there is nothing listening on port 51820, even though the port is open in the firewall and the wireguard interface is running. I basically copied and pasted the instructions to ensure I got everything right. nc -zv [server address] 51820
says nc: can't connect to remote host (xxxx): Connection refused
even though wg show says:
wg show
interface: wg0
public key: XXXXX
private key: (hidden)
listening port: 51820
Does anyone have a suggestion what I could try? This is strange, isn't it?
WireGuard uses UDP. Netcat needs -u for udp communication.
It's also worth noting that WireGuard tries to be silent on "bad" traffic. If with -u you receive connection refused, then likely wireguard is not listening. If nothing happens, then likely wireguard is on and silently ignoring "bad" input messages.
To be clear (since there's been no further responses), your Wireguard screenshot shows that the peers can communicate with your OpenWrt device. It's working.