I need help

Good afternoon, I have two servers on a dedicated server, one for testing and the other for the official server, but something strange has been happening to me for some time now, when you enter the domain to enter the official server it shows “failed to load server name” and when you try to connect later it comes out as off if I have the test server turned off and on if the test server is on, I tried everything, from changing the dns to changing the ports and it keeps happening, does anyone know how to help me please?