I accidentally deleted some certificates from the Keychain Access application and I think they were somehow related to WiFi networks. Now everytime I try to join a network that uses PEAP authentication, it tells me to Accept the certificate (no password to unlock).
I looked at Why does OS X repeatedly prompt for certificate trust when joining WPA2 Enterprise WiFi and added all the certificates as trusted, but that doesn't help.
Also, I suspect that this has caused my WiFi to become less reliable, i.e. my connection drops more frequently, and things like that.
How do I solve this? Any ideas welcome.