Node not found when connecting my nodes to each other


I’m running two Umbrel nodes with Debian 11.
Both nodes are fully synced since a couple of days.
I’m using Thunder Hub and try to add my nodes as peers to each other but I only get “Node not found”.
I have added other peers to my nodes without problems and I see other nodes as peers as I have not added by my self.
I had a friend trying to add my nodes as peers but he also got “Node not found”.
I have checked the debug log-file and everything seems to be up and running.
What is the problem?

Problem solved. It was a network issue. I had to do a portforwarding on port 9735.