'Failed to establish SSH session' error ; unable ssh via Ezeelogin shell 

• Make sure iptables / firewall is not blocking ssh traffic (check ssh port is open on both gateway & target server) and make sure SSHD is not blocked in /etc/hosts.allow or /etc/hosts.deny
• Make sure that SELinux is disabled on jumpbox / gateway server and the target server. You can find it by typing 'sestatus'
• Increase ssh timeout value to 60 seconds. Do refer to this user manual.
• Check ezsh log for errors. You can get it from '/home/{username}/ezsh.log '
• Also, check for the SSHD error log of the remote server to which you are trying to login.

• On the remote server run the below command.

• Try to re-add the server and try to access it again.