Telnet: Unable to connect to remote host: No route to host

Hi,

since few month i don’t get a SMTP Connection anymore. Firewall, both Servers i.e. turn off, still no Connections. Can’t ping each other.

# telnet mailserver.com 25

Trying xx.xx.xx.xx (my IP) ...

telnet: Unable to connect to remote host: No route to host

Does anyone has an Idea?
I use Ubuntu 18.x i think and latest Bitwarden.
Login into Admin with Mail returns Error 500.
Using UFW and Ports are open.