web rtc just audio works from android to ios

I am using a webRTC demo from this site

https://appr.tc/ source

it works from computer browser to ios mobile/safari (video-audio)

it also works from android to android (video-audio)

but from android to iOS (safari), I get no video, just sound

with below error:

WSS->C: {"msg":"{\"type\":\"candidate\",\"label\":0,\"id\":\"audio\",\"candidate\":\"\"}","error":""}

addIceCandidate: OperationError: Expect line: candidate:<candidate-str>

how can I have the webRTC video call working from iOS/safari to android?