TWU's WiFi is different from your home WiFi, because TWU's WiFi must handle thousands of untrusted devices being attached at same time. In order for WiFi to work without causing security problems or overwhelming the radio spectrum the devices attached to WiFi are not allowed to talk with each other.
- This keeps your device safer because it makes it next to impossible for virus-infected devices to infect other devices through the WiFi.
- This also makes WiFi work better because everything connected to WiFi normally sends occasional "broadcast messages" that would go to every device attached to the WiFi. These messages don't create any problems when you have only have a few devices sending them, but when you have thousands of devices sending them they would bring WiFi to a crawl.
Therefore, while you can add printer to TWU WiFi, it generally will not work because peer to peer networking is blocked on TWU WiFi for security reasons and to prevent the broadcast messages from every device on WiFi from degrading everyone's WiFi experience.
If you are living or working on campus, generally the easiest way to connect your printer is to use a USB connection. If you are trying to setup a printer for a group of people then using a printer that has a wired ethernet port connected to a TWU ethernet connection on the wall is the best option.