video call doesnt work after 30 min. in ms teams - but why?

Hello everyone! 

I have a problem in Microsoft Teams: When I'm starting a video call with my colleagues, my video is freezing after 30 min. and doesn't work. So for now I have the only choice using video call for 30 min within 24 hours. Do someone else has the same problem or can someone help me out? Thanks! 

Best wishes and stay healthy,

Dilara