Can't Connect to Server

This morning I tried to log into my aternos server and everytime I went to join it it just said "Unknown Host Name." Keep in mind that I was playing this server last night with my sister before we had to go to bed. I didn't make any changes to the ip address and I even tried to direct connect. I did everything that the aternos help page said I should do and nothing worked. I also tried to log in on a different computer and it still said the same thing. Also yes the server was online. Does anyone know how to fix this?