After testing for a few days I found out that indeed the Host / Join Session behaves differently in 4.22 than in 4.23 on the Oculus Quest.
I setup identical projects, checked the android intermediate manifest files for android permissions and such, and followed all the Oculus setup instructions. I even found out that if you don’t have Oculus Software installed on your PC that you can’t even see the OculusVR plugin options in Unreal 4.23! I only ever developed for the Quest so never needed it.
Both of the project settings are the same but they behave differently. I am able to host a session on the Quest, discover it by another Quest, but when I try to join it I cannot. The success pin even fires off the Join Session node when I try to join but nothing happens. How can it succeed when nothing has happened? I built the same projects out to Vive/Rift and if I host from a PC, I can join the server from the Quests in both 4.22 and 4.23. But as a Host, the Quest no longer works.
What has change with Oculus/Android related network permissions in from 4.22 to 4.23?