Everytime I try to join my Friend's "Friends Only" Server, the game tells me that I can't join because I'm not the host's friend.
But the game does know we're friends, because it puts the hosted game at the top of the list when browsing. It also only shows that server when you filter it by "Friends".
This only started happening after the latest DST update AND the latest firmware update for PS4 and PS5. My friend is playing on PS4 and I'm playing on PS5, but we never had any issues before these 2 updates. We're both online (not appearing offline) and when you look at my friend's profile through the PS5 game base, it says that they are playing DST and are "joinable". I've tried joining through the game (browse games) and I've tried joining through PS5 game base. Both result in the same error message.
The PS5 firmware update did change something to the way friends and parties work, so maybe something was affected in terms of identifying who's a friend and who isn't.
Go to Browse Games
See Friend's game at the top of the list, choose it and join the game
Message that server is set to Friends Only and that I am not a Friend of the host