Jellyfin getting blocked on client device using VPN

[LJDR17]

Hi guys, I have Jellyfin successfully setup and working on my home server, utilising PiVPN using Wireguard for access outside of my LAN. When testing this using my 4G on my phone connected to the VPN, it works perfectly and connects to Jellyfin. However, when when another user attempts to join from another network while connected to the VPN, they get an error page on chrome saying their internet access has been blocked and that the antivirus or firewall may be blocking the connection. Upon turning off the firewall on their device, this error still persists. Does anyone know how this potentially could be fixed, thanks!

[TheDreadPirate]

Which wireguard client are they using? This sounds like they aren't using a legit wireguard client or something.