Hi. This happens. There may be several causes.
1. Your internet connection is simply too slow. Please verify it on some free speed testers. For example speed.io. What you need to check is also the upload speed and the jitter. The exam transfers the desktop (the amount of data depends on your resolution, so do not set anything larger than full HD), sound, and video. Jitter refers to quality. Although you may pass the compatibility test with speeds like 1.5Mbps up and down, I recommend you to have 10/10 Mbps at least. You want to focus on the exam tasks, not the laggy environment.
2. You say you checked with multiple networks. Was your computer network card still the same? If so, change it. Go to wired Ethernet, avoid wifi, and do never use a 4G mobile hotspot or similar technology. It will not work. Check the link speed od the adapter in the settings. Your network adapter may not be fully compatible with the Fedora you are booting from the USB stick for the exam. It may run at some degraded speed or older mode. This may meaningfully affect the speed. If you can, use a USB to Ethernet adapter and try again.
3. Change the camera. I am not sure but I assume some firewall block or incompatibility may force the camera video stream to use TCP instead of UDP connection and this would actually consume the whole bandwidth.
4. Some proxy, air device, firewall, and traffic shaper devices in place affect the network performance.
5. Video card compatibility. Working as a support member, I have seen cases when the nonaccelerated video had a very negative performance effect on the exam. I assume Firefox can use graphics card HW acceleration and there is a problem, if it does not, for some reason. But this is just unconfirmed speculation.
I hope some of this helps
Petr Cihlar
