Why does the session hang when I try to connect to a remote server via SSH?

Question

SSH

When connecting to a remote server, the ssh session hangs. When the timeout expires, it closes. At the same time, outgoing connections from the server work without problems. The server has a white address.
[email protected]:~$ ssh [email protected] -p 33xxx -vvv
OpenSSH_7.2p2 Ubuntu-4ubuntu2.10, OpenSSL 1.0.2g 1 Mar 2016
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: Applying options for *
debug2: resolving "95.173.x.x" port 33xxx
debug2: ssh_connect_direct: needpriv 0
debug1: Connecting to 95.173.x.x [95.173.x.x] port 33xxx
ssh : connect to host 95.173.x.x port 33xxx: Connection timed out

Answer 1

I solved the problem by changing the port (to the standard one). I am using key authentication. As soon as I change it back to a custom port, another session hangs up ..
Although in all firewalls (iptables, watchguard) there are permissions for sssh only for a custom port. Ports are listening (standard and custom). Magic...

Answer 2

It looks like it's not available at the network level. Check if the port is listening, if it is open on the firewall, etc.