Captive portal and IAS 2003

[Asterisk]

I've solved the other problem, it was that in dhcp config, DNS server it wasn't pfSense ip.
Now it works perfectly, but if i restart my AD server, after reboot i can't authenticate clients, in event viewer i got ID event 13 on IAS, but if i restart IAS service, all works well again.
Could i know why? :-)

Log when it fails

logportalauth[526]: ERROR: paperino, 00:1c:bf:82:f7:2e, 192.168.1.253, Error sending request: No valid RADIUS responses received

Log when it works

logportalauth[526]: USER LOGIN: paperino, 00:1c:bf:82:f7:2e, 192.168.1.253

and on event viewer (italian)

È stato ricevuto un messaggio RADIUS da un indirizzo IP non valido 192.168.0.1 del client RADIUS.

traslate like It's received and radius messages from an not valid ip address 192.168.0.1 of client RADIUS.

But in my pfSense i have Windows DNS setted up