Can't connect to PMS.



suddenly I cannot connect to my PMS. I checked through the ssh the server is running. I cannot connect to my PMS through web, apps and neither through the account.
I tried connecting through LAN and the Internet - nothing.

I've been using this server for over two years now. Never have I had any problems connecting to it.
Any idea...? Please...

My server runs Linux 16.04 LTS, with LAMP.