problem in voip application using QT

I write an application to send a voice from client to client in real time in the two directions but the problem in my code that the sound late as long as the application work it delay for some seconds each one or two minutes and I don't know why I get my project codes from an open source project on Github but it works only in one direction that server sends voice and any number of clients receive it only but I need the client to send and receive the voice in real time so I modify the code to do that the problem found too when I release it on android I need an expert c++ Qt programmer to fix my problem in voice transfer I attach both the code I modify and the project found on GitHub if anything not clear send to me, please I need to solve this bug as soon as possible, and I need the simplest solution