Issue joining my own server using my account

I made a server on aternos and tried to join in using my own account. For a while, it worked, but then I couldn't log into most of the servers I had because it kept saying "Can't resolve hostname". I thought it was an issue with aternos, but when I tried to join using a friend's Minecraft account, I could join the server and the other servers which I couldn't join. I have attached an image of what keeps coming every time I try to join any server using my account. Please help, thank you!