Thank you for contacting Promethean Technical Support.
To better assist you with the issue reported, we kindly ask you to confirm what kind of device and operating systems the students are using to share their content via Screen Share on the ActivPanel. Have you tested different devices? Does the same issue occur?
If this happens on other devices as well, you may want to ensure that your network is properly configured. The following article on our Support Portal provides guidance on how to configure your network when using Screen Share: https://support.prometheanworld.com/article/1796/.
It may also be worth trying a Wi-Fi hotspot with a mobile phone to see if it’s something to do with the school network.