Server not reachable

[foeke]

One of the servers running 7.0 is not reachable.
Can't open the shares, can't ssh, can't open the web console.
It is pingable. But it takes a whole while before it starts.
Internet still works. Full bandwidth.
And OVPN is also still working fine.
When I try to connect with Putty, it takes a while before it asks for the username. Then even longer for the password.
Just once I could log in, and I tried to restart the firewall first. But that didn't happen. I don't know if it started that processes.
Any suggestions?

[foeke]

If this problem doesn't return, it was most probably because some eternal party crammed 3 other servers in my clients little server cabinet. And the server was just overheating. A reboot outside the cabinet solved it for now.