I use Mullvad, and yesterday I started getting a 502 Bad Gateway error whenever I tried to visit the site when connected using Wireguard. Oddly enough, OpenVPN works fine. Are the admins intentionally trying to block VPN access, or did Mullvad's Wireguard servers get caught up in some sort of filter?
I got something similar, as I use ProtonVPN. I had repeated 502 errors.