I’m working on a similar thing.
I had that problem as well but solved it due to my host session > Open Level options. I had it on “-listen” but they just needed “listen”.
For now I can host on my PC and join using one Quest that’s connected to the same wifi network.
My problem now is that when i want to connect a second Quest client, the host crashes and unreal editor crashes. I have no idea what’s wrong.
Do let me know how yours is going and if this helps!