I have not had that issue specifically. However, I have had them use a computer that I have logged into so that they can access the materials they want to upload. Then when they are shared as a class, we use my computer again so that everything works. When they work on them at home, they don't have the firewall access issue, so it isn't a problem. I have asked to have the firewall lessened for specific class periods for specific students, but this is not able to be done. I hope that helps.