Player on my Server is glitching trough map

Hey there! I’m a server owner. One player on my server is glitching trough the map sometimes (sometimes even 3 times or so in a row). The weird thing is no other players have this problem. Also there is another player in the same network as the player having the issues and he doesn’t have this problem. So it cannot be the internet connection of the Person (or only the network card in the pc). Also the PC is not the baddest (Intel i5-6200u, GTX 950m, 16GB RAM). We’ve already changed the graphic settings to the lowest. Any other ideas?

Edit: We’ve also tried to go on a test server (identical to the main server) and disabled most of the addon cars and maps.

That “PC” is a laptop by the looks of it, so I think that’s your answer.
Another guess is that it’s slow DDR3 ram + HDD.

common issue. if your internet connection is bad or you have a bad PC. you may glitch through the mapp and fall down the map. if im not wrong there was an resource to teleport you back

Yeah, ik. But another weird thing (which I fugured out later) is, that the player also played on another Server with 400 players and much NPC traffic. And there everything was fine.