Are you using UIWebView in your iOS project rather than WKWebView?, May be it causes for on iPhones, cams can be broadcast with Safari, but Chrome and Firefox does not work
Since, according to this Google support link Chrome on iOS is using WKWebView which is basically a limited Safari version controlled entirely by Apple.
On iOS 11 Apple implemented the WebRTC protocol for Safari, but they didn't do it for WKWebView.
It's a shame because all non Safari browsers (Chrome, Firefox, etc) has use UIWebView and even inApp browsers are constrained to this engine (ex: Facebook, WhatApp, etc). And unfortunately, from what I read on Apple's site, there is no plan to integrate shortly WebRTC support in WKWebView. Hence the only thing left for us is to put the naive UIWebView and remove the existed WKWebView for web engine.
also
Before I was getting the similar problem which is, making a WebRTC connection between others (Chrome, EI and Firefox) and iOS/Safari not working:
Reason:
no H.264 implementation on device
Chrome, EI and Firefox has only a hardware implementation for H.264 and there is no software implementation. At this moment since Apple only supports H.264 other browser can't connect with iOS and Safari.
In this case, I've fixed the communication between all non Safari browsers( Chrome, EI and Firefox) and Safari by adding "playsinline" inside < video > and changing the methods "handleRemoteStreamAdded(event)" and "gotStream(stream)"