you need to have psn+ on all accounts active
Not sure what you mean? I have ps+ active pretty much since the start. Hence 1497 licenses from always adding the ps+ 'free' games. But the other accounts have a simple psn account. They don't need ps+ to play couch co-op with me, don't even need it to play online together, or alone on the 'primary' ps5.
When we couldn't play together in the living room, my oldest went back to play Minecraft dungeons with his online friends on the 'primary' ps5, while the one in the living room refused to start the game at all. Once the license server started working again, I could launch Minecraft dungeons while he kept playing on the other ps5 without any issues.
Anyway my wife and I continued with Dragon's Crown Pro since the kids were both in different games with their friends.
Another mystery. My oldest can play with friend A and B online in p2p games, yet not with friend C. Friend C can also play with A and B, and that way my oldest and his friend C can play together. But if my oldest or friend C hosts the game, it doesn't work. (A and B can always connect). There is no issue with games that use an actual server like Rust, yet anything that's hosted locally is a problem.
We're going to try to swap the PS5s to see if that might help, but I suspect it's something in the network settings. My oldest and friend C could play together fine before C moved to Vancouver (other side of the country). So what changed, must be a network setting, but what.
It could be a time out problem of something. My son says it worked once in Terraria, C hosting the server, after trying for hours to connect. Hasn't worked since.