NPS PEAP MSChapv2 Access-Challange Problem

Hi,

i hope you can help me.
We have a wlan infrastructure with PEAP and MSCHAPv2authentication. That still works fine internally.
As we participate in the Eduroam, you can log in at other academic institutions.To February it all worked perfectly. But since March, I get Access-Challenge messages from the NPS sent to the Radiusproxy and the authentification fail.
In the NPS Logs are no entries for the user that try to connect.

you have any ideas?

RadiusProxy Logs

Mar 10 08:47:38 2014: Access-Request with username: aduser@local.domain.de
Mar 10 08:47:38 2014: found matching realm: /@local\.domain\.de$
Mar 10 08:47:38 2014: found matching conf: NPS
Mar 10 08:47:38 2014: sendrq: inserting packet with id 171 in queue for NPS
Mar 10 08:47:38 2014: sendrq: signalling client writer
Mar 10 08:47:38 2014: clientwr: got new request
Mar 10 08:47:38 2014: clienradputudp: sent UDP of length 307 to NPSIPAddress port 1812
Mar 10 08:47:38 2014: freerealm: called with refcount 4
Mar 10 08:47:38 2014: radudpget: got 94 bytes from NPSIPAddress
Mar 10 08:47:38 2014: buf2radmsg: message auth ok
Mar 10 08:47:38 2014: got Access-Challenge message with id 171

regards

Micha