Hi Thomas,
Before I forget, please when talking about a problem, be sure to include the freeradius version.
If in freeradius 3, be sure that in mods-enabled/eap you have commented ca_file and ca_path. I had the same problem in iOS, and I could *swear* it was that. Let me know if it helps.
iOS and in particular iPhones are much more picky about this kind of stuff than other platforms. I could swear that for the intermediate certificates Terena is giving was the intermediate chain was not there before iOS 8.0. So I had to build a certificate with the complete chain for the RADIUS service.
Regards,
Rui Ribeiro