arch-choot parent
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.