help Can''t play games on the same router

[RAAL4]

whenever i try to join a BF4 or BF1 server with my brother randomly one of us gets in to the server and the other gets a generic error. but almost never do both of us get to play on the same server. we can join individual servers separately, and be playing the game at the same time, but when we try to join the same server it only lets one of us in. i suspect it has something to do with our router setup because it never happens when playing with friends on different routers or internet connections. we are trying to play rainbow six siege now. I have never had a problem with the servers except when i try to play with my brothers. we have a lobby of 5 guys, start a game and ubi will either give everyone the error "a squad member has encountered an error" or it will only allow 1 of the 3 people on the router to join the game. again we can all play in parties normally, as long as that person is on a different network. and we can also play public matches solo. but as soon as we try to play together we all get the same error that means nothing or 2 people get kicked and 1 gets in. we are all wired and have the same IP address, the IPv4 addressees are all different. they end in 1.10         1.12       1.15. we have a netgear r700, 300Mbps download and 30Mbps upload, QoS turned off and UPnP enabled. please help