Re:Let's Encrypt has issued its first million certificates
by Ao7bei3s on Tuesday March 08, 2016 @02:25PM
(#11247791)
At least modern Android version support setting the CA certificate in the wifi settings.
(And then there's the university way of things: just run your own trusted (!) CA ;-) (e.g. in Germany: signed by DFN)
This is the most annoying part of using certs for Radius authentication with Android. Either you self-sign a cert and forever get these warnings, or you let someone else sign your cert and then that CA can issue device certs for your domain.