Can anyone tell me why some computers display online and other computers do not

[James2000k]

I have a copy of teamviewer and i have a few computers connected to. The issue i am having is other computers immediately
display that they are online and i can connect to them. However other computers do not even though the computers are turned on and connected online
I sometimes have to either relaunch the team viewer app and then the computer is visible on display and i can connect to it

Does anyone know if this is a setting that has to be enabled and if so how do you get to it