Connecting to a PC with no screen connected to it, set resolution?

I have a Windows Server 2016 with no keyboard, mouse of screen. When I connect to it I can only see 640x480 and it is not possible to change to anything else, but as soon as I connect a screen to the server I get the that screens resolution, but, as soon as I unplug, and disconnect, the next time it is only 640x480 that are awailable again, can I fix this?