I thought the AOE2DE based on Client-Server technology and someone have bad internet connection just that person will lag, others will play no problem.
But in the game only one player has little red clock icon then entire game (all players) lagging.
(ATTACH A SCREENSHOT IF YOU ARE ABLE!) (BONUS: ATTACH A VIDEO OF THE PROBLEM HAPPENING) (ATTACH YOUR DXDIAG IF YOU ARE ENCOUNTERING A TECHNICAL ISSUE) (ATTACH ANY CRASH/GAME LOGS [IF RELEVANT])
This is not network lag, this is CPU lag. All players must run the game at the same rate, otherwise the slow player will fall too far behind and the game will desync.
Servers are there to mitigate the effect of network lag, but make no difference if one PC can’t keep up.