Reasons for "MS-CHAP2-Response is incorrect"

[Sven Hartge]

Hi all!

The 1st level support group here has asked me to clarify the reasons
behind authentication errors where the message is "mschap:
MS-CHAP2-Response is incorrect" so they can better point the end users
in the right direction.

The obvious one is of course "wrong password", another one is "mucking
about with the Username in the RADIUS server" (which I don't do).

What other reasons are there for this error type to occur?

Grüße,
Sven.