Docker image SSL port 3000 cannot be reached via VPN

Could someone please help me to fix the following issue ?

I have an instance of Gitea that runs perfectly fine as a Docker container (“official” image) using SSL on port 3000.

The issue is that users who use a VPN get ERR_TUNNEL_CONNECTION_FAILED . When they turn off their VPN, everything works fine.

The issue is for users who cannot disable the VPN, using for example a corporate PC.

Any clues would be appreciated.

Thank you in advance.