The network of computers run out of the Computer Engineering Research Group at UofT ECE. It runs Debian with a fairly old version of GNOME.
VNC connections can be made via clients. iCtrl is a good one since it’s tailored to the UG machines. SSH connections can be made to ugxx.eecg.toronto.edu where xx is a number up to ~250.
Occasionally a Firefox bug happens where you can’t open the browser on the physical machine or via VNC. There’s no clear workaround but in general this is because it’s open in two different versions of the machine — the physical machine or the VNC. When done with work on either one, close Firefox before logging out.