Hello,
Immediately after the release of the new Hub 4, I set up a new server with it: great, thanks to everyone involved! I didnât want to ask with the first post either: it doesnât work, what do I have to do 
Everything seems to work!
nextcloud: 26.0.1 (started from 26.0.0 with latest.tar.bz2)
Talk: 16.0.3
notify_push: 0.6.2 (redis, proxy, self test: ok)
debian: 11.6
php: 8.1.17 (via sury)
However, I noticed that desktop notifications in Windows- and Mac-Firefox do not arrive, if the currently ACTIVE discussion group is open in the talk: at least I see (a long) time later the blue bubble. When I switch to another NON-ACTIVE session: blue bubble, red notification point, system sound and system message come with new posts: perfect 
That sounds so strangely systematic that there is definitely a solution?
Workaround: I always keep a dummy talk-group ACTIVE in betweenâŚ
It always seems to work in iOS on iPhone and in the iOS app on Mac.