I currently have a Roku Express (3700 series) that worked on the university wifi last year, but now the connection isn't showing up as an option. The wifi that the school uses requires us to register the device on our student accounts using the mac address, which I've already done, several times. Is there a way to fix this? Or am I stuck without my roku until I'm back home
At home I've had several times when my home wifi network was not detected by my Roku. I've always been able to correct this by restarting my router and then my Roku. But I suspect you have no way to restart the school's router.
See if this will get it for you:
Settings > System > Advanced system settings > Network connection reset
This should clear out all stored network information and if you're lucky will remove whatever is blocking your Roku from seeing you school's wifi.
Since you say you have an Express, there is one other possibility that comes to mind. Express and Premiere are budget models have single band wifi radios operating in the 2.4 GHz band. If, since last year, the school has switched its wifi to only the 5 GHz band, your Express can't work with it. Most (all?) router systems supporting 5 GHz also support 2.4 GHz, although this may be turned off -- you might want to check with the system's administrators about this.
bad news