Fix Android app issue built on java ( agora api )

Hello i have hired someone to développe an app , but now we are facing an issue that he couldnt fix .. let me explain the app first : its an app that is like Tinder and azar ( random vidéo chat ) AT same Time .. but the random vidéo chat has some issues :

1- it has difficulties to connect between users
2- it shows wrong names or sometimes even wrong caméras for multiple users .

And we want to fix that

Its built on java and we're using agora api