So I coded that the game started once the other user send a comeback with the UTC time. So I coded that both games should start at UTC+3Seconds (currentTimeMillis()+3000). When I try it on desktop (I use libgdx) it works fine, but when I start it on different mobiles, one mobile is starting 1sec after the other one. Both are good devices etc and I dont understant the problem... One device is a OnePlus 3 and the other is a Nexus 5. Any advice? I am just confused because on desktop it works well.