I was applying some STIGs to our hosts and ran into a problem the next day. When I try to SSH to the host I immediately get the following message "server unexpectedly closed network connection". I was modifying the advanced settings through vcenter but I was also modifying the passwd and sshd_config files through SSH. None of those I can find would cause this problem. I did the same changes to two different sites and I can still access the other site over SSH. I made sure the SSH service was on and that lockdown mode was disabled before trying the SSH connection. If it was a typo of some sort I am not sure what it could be. There are 3 servers at this one site and i cannot access any of them. I did not do a restart on the sshd_config or reboot the hosts so those changes should not have taken place yet.
I can provide the list of changes made if needed but i was wondering if anyone had an idea about what would be preventing the ssh connections.
Maybe, Firewall setting on your ESXi host. Look at if a IP filter is apply on SSH firewall setting or if your Firewall is on.