The campus I work for (I'm a student, not faculty or staff) is having issues with iOS 10 (for sure, haven't been able to get a single device running iOS 10 to work, even though 9.x.x worked just fine. It instantly says "Unable to join network" every time you tap the network name) and allegedly Mac OS Sierra not connecting to their 802.1x WPA2 Enterprise network. In doing some troubleshooting in my own personal time, I discovered that their certificate is self-signed. Could this be contributing to the issue?
Found out the issue was indeed the RADIUS certificate, as Apple deprecated the SSLv3 cryptographic protocol and the RC4 symmetric cipher suite in iOS 10 and macOS Sierra.
FYI SSLv3 and RC4 are related to transport, not certificate signing. So the issue probably is more related to building the EAP tunnel to the RADIUS server or processing authentication, not the certificate verification.
It's common to see self-signed certificates in these deployments because the CA requirements vary among different clients, so it's considered easier to just use a certificate that will essentially never expire