I am having the same issue, or a very very similar one.
I installed ubuntu server and followed instructions here: https://docs.cloudron.io/installation/
But I am stuck at this step :
Once installation is complete, navigate to https://<IP> in your browser and accept the self-signed certificate.
It get stuck at loading until I get a "connection has timed out" error
Installation went OK and I can open the setup page using the local ip, so I guess the issue is with my ISP router
I am in France and the provider is "Orange"
I associated a fixed local IP to my server mac address in the livebox settings under DHCP/DNS .
And I also created rules to forward ports 80 and 443 under NAT/PAT but then I removed those in case it was messing with UPnP (wich is enabled by the way).
None of that worked
Can you help me ?
P.S. I registered an account on the chat since the OP question was resolved there but I do not have access to it yet
@uc3wi I don't really know the settings for your router, but hitting a timeout while trying to access your server using your public IP on port 80 could mean that this route isn't working correctly. As said I don't know how the Orange network work, but make sure to have a real IPv4. At least some providers in Germany would only give a shared IPv4 for cable connections by default, and here you have to ask the ISP to assign a real IPv4 for that to work.
AFAIK, Orange does give normal IPv4 IPs to its customers. I believe the problem here is "hairpinning", where the router does not redirect the ports to the correct local IP when accessed from the public IP inside the local network. Not sure how you can solve it, sorry. Maybe just use the local IP for the setup, and add a local hostname to your router's DNS server for the local IP instead of the public one ?