Hi: I had used freeradius EAP-PEAP-MSCHAPv2 + EAP-PEAP-GTC with Wi-Fi for several years. I had a concept in mind (which seems wrong) that a client would send EAP requests blindly. so client and server should set up correct EAP type parameters before connection. When I found that Win10 supports EAP-TTLS natively, I tried to use it. and I found that when I switch EAP-PEAP/EAP-TTLS settings at freeradius, Win10 and IOS/MacOS would detect it automatically and use the correct EAP type. I use "radiusd -X" to monitor the traffic, it seems freeradius would send something to the client at first response, although I don't know what's inside the EAP Message. I found Win10 will auto detect/support EAP-PEAP-MSCHAPv2/PEAP-TTLS-GTC/PEAP-TTLS-PAP. IOS/MacOS will auto detect/support EAP-PEAP-MSCHAPv2/EAP-PEAP-GTC/EAP-TTLS-GTC. but IOS/MacOS didn't detect EAP-TTLS-PAP. so I don't know if "default_eap_type = pap" is a correct parameter under the ttls section. Win10/Win11 will auto detect and accept PEAP-TTLS-GTC as PEAP-TTLS-PAP which seems strange but a good thing to me.Android seems lazy and doesn't auto-detect anything and just wants the user to input EAP parameters manually. Is there documents about what's behind the scene? Can I decode the EAP Message to know what information is exchanged between client and server? Thanks a lot for the clarification!! Regards, tbskyd