No stable connection for videocall on AirCard 810S Mobile Hotspot

Just bought an AirCard810S Mobile Hotspot. No problem setting it up and the internet connection works fine on mobile and computer until I tried videocalls. As soon as I establish a videocall via Microsoft Teams or Zoom the connection is not stable enough.

I am using the same simcard and placement (window in the city) as with my prior mobil hotspot where I had no problems with the connection for videocall.

Does anyone knows if the AirCard810S Mobile Hotspot is not able to create a strong enough internet connection for videocall?

Thank you