VPS stops responding

Hello! I tried Virtualmin and really like it. I’m learning it fo several days and today had a very strange problem. I have VPS with Virtualmin. A virtual server, with the domain stops responding in browser. I rebooted the server and after that I couldn’t connect not to the web-interface, not even via SSH. I can ping the server and its alive, but I guess its dead for me cause there is no other way to do something except ssh. Ill reinstall everything, but could this thing happen again?

After some researching I guess its linux firewall blocked all ports. Have the same issue on fresh Vmin install on Debian 8.10.