I have the same problem but with different Devices from Windows Pc Running chrome trying to remote Preview to any iPhone Devices I got the same problem as you described "get stuck during Connecting" I had to restart many Times it can get really frustrating, sometimes it starts loading but slow and after long waiting gets stuck it really slows down the development quite a lot making it nearly impossible to carry on with the Game, I just recently tried again with the "Game Jam" and still behaves the same, I thought it would be fixed by now.
Is it a coincidence that it only happens when you trying to connect ios devices?
I never tried android so I don't know if behaves the same
My internet is not the fastest but I download at (2 or 3) MB per second up to 8 MB, I don't think is a problem with the Internet
There is a request to bring back the C2 Local Preview which works pretty good I never had any problem with it, if you are interested please Vote
Link:
https://construct3.ideas.aha.io/ideas/C3-I-618