My friend is always out of sync when we play

[plush owl]

Since the last update where ALT//R3 was added, one of our friends in our group of 4 takes a long time to join into our lobby.
When he eventually does and we start the mission, he is out of sync with us.

Chests we open, are opened way later for him, enemies are completely out of sync, his weapon shots, everything is out of sync.

Things we already tried:

• reinstalling the game
• hosting with different persons
• adjusting router settings, router restart(though he could play other games without a problem online)

Something to notice: Yesterday we wanted to test if the issue still exists and I only started the mission with him (this was around 1 pm) and everything felt like it worked. Later that day when we wanted to play as a whole group, the issue came back.

[wary spindle]

If i were going to make an assumption and im by no means an expert i'd say since gtfo is peer to peer its a problem of say him connecting to someone like say he can connect to 2/3 of you just fine but thats last person is hard because some reason like i know some usa networks restrict peer to peer connections or something? (what i was told and roughly remeber) if the 2/3 fine and the last 1 connecting is bad its just a matter of switching host i think possibly a fix but if its like he only connects to you fine then maby you have to be the middle ground of everyone has average delay so he doesnt have bad delay,anyways thats just some guess work i have if anyone who ya know knows about the stuff makes a comment trust there comment over mine cause again no expert