Black screen within private network

We have an OpenVidu Pro installation set up for use in healthcare. Things were working great until one of our clients tried to make a video call from within the hospital’s private network. The call is connected correctly, but the video is just a black screen.

Could this be an issue with the hospital’s firewall? What ports do I need to ensure are open?

i think this is due to turn detection problem in private network by firewall i seen many times before 2.16.0 but now i thoughts its over can you share logs of console and server
Thanks