I've been thinking about this a long time, and I don't have an idea how to fix this.
So, I can't join in the same game with my friend. My GTA online works perfectly, I can join in the same game with my friends and crew, except my one friend. I've been in the same game with him a few times when GTA online got released and it worked well back then, but now it doesn't. Always when I try to join his game, it says "Unable to connect" or something like that. Same happens when he tries to join to my game. Few times we tried to connect to the same game at the same time, I got there first and when he got in the game, I got 'kicked' and my game said there was some kind of network error. Is there any way to fix this? I would really like to play with him.
I can give you more information if you need.
I also don't have a router, I have some kind of USB modem.