I try some demos:
PalladiumGames
PalladinStudios
And I install game to android phone and computer and I can’t join game.(I also use port forwarding and and I was on same Wi-fi, and I turn firewall off)
I dont’ know what can be problem. 
And I tried join from computer to computer.
Please can you help me?
By that tutorial, it has in the code: “ConnectionIP: 127.0.0.1”, you’re changing that, right?
Because, 127.0.0.1 AKA localhost is the device/computer that it’s running from. So, you’d be trying to connect to…itself.
ASSUMING you did however change that IP, are you trying to connect to your external IP or an internal IP (The one the router gave your internal devices)?
You could diagnose the issue, by bypassing the router all together, and either have a friend try to connect to your IP (whatismyip.com), or use your mobile’s data and connect.