I own a realm and multiple apple devices.  I cannot connect tonmy realm while using any of my iphone 12 pro models, one running iOS 14.2 and the other running iOS 14.3.  I have no issues connecting on iphone 8s running either iOS 14.3 or 14.2.  I can also successfully connect on my ipad pro 12.9 3rd and fourth gen models.  The realm can be downloaded as a backup.  After the “loading resources” appears the app crashes to the background.  I can play single player without issue.  I also submitted as support request (1690365).  This is not a privacy issues with iphone as I have enabled local network communication in settings.