Can’t Play Multi Player with S.O.

[Jessieraenola]

Got a strange problem and I’m not sure if anyone else has encountered it. 
 

My S.O. Has had 7 days to die for years and got me into it last year. We’ve been playing split screen for a long while, but bought another PS4 for our bedroom about 6 months ago so that we could play the online multiplayer and do a private game for just us. 
 

well…it doesn’t work. We’re unable to play together in the same house. We’ve played a private game with brother and sister in law (who are both in one household as well) and we can play if they start the game and Invite us. They can also play online just the two of them, in their one house, so I know it’s not impossible. 
 

what am I missing here? 
 

we’ve confirmed that we have enough speed to connect, and both hardwired into modems for confirmation. Getting ~300 mbps on both of the systems yet still can’t connect online together in 7DTD.