Problems/bugs with multiplayer

A couple of my buddies picked up the game recently so we've all been playing together. It seemed to be working just fine on the first day (IRL) but then last night both my mates were getting desync problems, parts of the map wouldn't render for them, they couldn't see my actual position (sometimes while I was running right beside them).

Anyone else suffering similar problems? Any tips on what I can do to fix it? Is it just down to shitty internets/lag?

I've assigned 16gb RAM when hosting (my PC has 32gb) each time, would lowering this help?