What is master server in unity is it okay to use it in my multiplayer??

I make a Multiplayer game base on this tutorial [null - YouTube]
and this tutorial is Via internet.

but im bothering me sometimes the List of the server not show… and im trying to test is so many times… in other Pc to PC and both Pc connected in one router with internet Via Lan

Help me please :frowning:

There’s a whole section about the Master Server in the manual