there was a problem with the Cloudron internal firewall. Once he changed the settings there, the connection was established with no problem.

Could you please elaborate what the issue was?
Do we need to fix something? Also, useful for future readers who have a similar issue.
I could bet you know the feeling of searching a solution and just finding a "I solved it, thanks" post somewhere and think yourself AND HOW?.

sorry for the delayed response. We initially had the problem that the Wireguard tunnel between an on premises system and a Cloudron Server on Hetzner couldn't be established.

The WG config was correct. We tried it on a different server on Hetzner with no problem. There seemed to be a problem with the Cloudron Server.

Then, my colleague figured out that there was a problem with the Cloudron internal firewall. Once he changed the settings there, the connection was established with no problem.

Thanks!
Arne

@arnej said in Problem with setting up a VPN tunnel from on premises machine to Cloudron in Cloud:

With that VM, our local machine was able to establish a connection.

This sentence confuses me a little.
A You did set up a VM on Hetzner with a Wireguard server and connected your on premise computer with that server
B You did connect a Hetzner VM to the Cloudron Wireguard

@arnej said in Problem with setting up a VPN tunnel from on premises machine to Cloudron in Cloud:

Do you have any idea why that may be?

Could this maybe be an issue with IPv6 and IPv4?
Can you share some insights if you use IPv6 local and in Cloudron?