Hmm that's werid, there's a suggestion that some public wi-fi networks block the inital wireguard handshake yet if you establish a tunnel on a different network (like cellular) then switch to that network then wireguard can communicate over it.

Seems to be the case with the public wi-fi here and my gl-inet slate4 if I connect my f50 and do the intial handshake over the ropey cellular I can then use the tunnel over the Wi-Fi.