I have two different devices, one running OpenWRT 19.07.8 and one running OpenWRT 21.02.2.
My device running OpenWRT 19.07.8 has a wireguard interface, it connects the tunnel directly not matter if wan or wwan0 interface has a working connection to the endpoint.
The other device running OpenWRT 21.02.2 only establish the wireguard interface it it has a connection over wan. Even if I have wwan0 and can ping the endpoint or manually create a route to the endpoint on wwan0 the wireguard interface does not even show up ?
Is it a bug or has something else changed that I am not aware of - I have tried using option tunlink 'wwan0' but it does not change anything.