Unfortunately watchOS 3.x can't connect to a Wi-Fi secured by WPA2-Enterprise.
I have experienced the same behavior in the past with watchOS 2.x as well.
- Your university's Wi-Fi is part of eduroam or uses a smiliar Wi-Fi login using your credentials (user name + password)
- Your university's Wi-Fi thus uses the WPA2-Enterprise security protocol
- You can connect to the Wi-Fi just fine with iOS devices like your iPhone
- You use an Apple Watch running watchOS 3.x
With iOS you can enter your credentials. They will get saved and can be transferred to watchOS. The certificate, however, cannot be provided from iOS to watchOS.
Let Apple Know
Contact Apple and let them know. Apple cares about user's feedback. Use Apple's feedback form for Apple Watch.
divB has pointed out that the network uses a MAC address filter instead of the WPA2-Enterprise security protocol
Please make sure to provide your Apple Watch's MAC address to your university as well as your iPhone's MAC address.
You can find it on your iPhone:
Watch.app > General > About > Wi-Fi Address