Cant seem to get reverse proxy working: Connection timed out Error code 522

Hello,

Today I tried getting my new server up and running through Proxmox LXC's and its generally going well except for vaultwarden. I made a certificate with a DNS challenge that uses the API key generated on the host.

I used *.domain.com with dns_cloudflare_api_token=API_KEY_HERE

That cert gets generated just fine and then I add a proxy host:

sub.domain.com
scheme: http
forward IP: internal.ip
port: 8000

SSL: use *.domain.com cert I generated in the first step.

But I keep getting: Connection timed out Error code 522 in the browser
I used this helper script: https://community-scripts.github.io/ProxmoxVE/scripts?id=vaultwarden

Does anyone have an idea what I do wrong?