I believe the same question was asked here: setup-of-pcs-on-lan-game-only-aoe-2-de
TLDR:
-
Make certain that the two machines are on the same local network (you are both connected to the same router either via wifi or ethernet cable).
-
Change the firewall settings (on both machines) and allow incoming communication on these ports:
Try just opening these ports first:
TCP Port 8888 , Port 3478 (UDP & TCP), Port 5222 (UDP & TCP)
and if they don’t work, then do all the below:
Age of Empires II: Definitive Edition - PC
- TCP: 3074,3478,5222
- UDP: 88,500,3074,3478,3544,4500,5222
Age of Empires II: Definitive Edition - Steam
- TCP: 3074,3478,5222,27015-27030,27036-27037
- UDP: 88,500,3074,3478,3544,4380,4500,5222,27000-27031,27036
- For some reason, it also appears for some people that both machines have to have a working internet connection in order to play LAN (can’t confirm or deny this)?