antonok parent
Funnily enough, I'm on a British Airways flight right this moment. I'm only using a basic Wireguard tunnel after enabling the free messaging plan. I get the sense they didn't design the firewall to block everything comprehensively.
Just bare wireguard on 51820? I think I had tried that but no luck; but I don't remember for sure.
I'm using a non-standard port (above 10000). Otherwise, nothing special about my configuration. Perhaps 51820 is blocked?
It is admittedly quite slow/intermittent though; I wouldn't be surprised if that's the reason it didn't look like it was working for you.