How to play multiplayer on same wifi AOE 2 :DE ?

Me and my cousin have bought the game yesterday on steam. ( Both on laptops) We used to play LAN back in days of AOE1&2.

Now our internet is shitty disconnects Sometimes in bw.

So, please tell me how to setup a multiplayer for my wifi network where we both can play.

My internet is fast but unstable. A step wise guide would be highly appreciated. I can't find anywhere.

Cheers to the villagers.