Enable browser-based connection to the student VMs, instead of RDP/SSH
I guess the nice thing about RDP files is that you can potentially get multi-monitor support and clipboard sharing just the same as using an on prem server RDP connection.
But https in a browser as an option would also be great, not everywhere will allow outbound port 3389 to the internet.
Sean Murthy commented
I welcome browser-based connections for any lab user because it eliminates the need to frequently download the RDP file.
I'm not really sure why the RDP file becomes unusable after a while: the only reason could be the domain/port changes (but why?). It is particularly painful because users customize RDP properties and they will need to redo that each time the RDP file changes.