USG210 VPN RADIUS Authentication failed

jw708 Posts: 9
We have an L2TP VPN set up on the ZyXEL that uses a RADIUS server and Azure for MFA. We seem to get issues sometimes where the ZyXEL logs:
RADIUS: Rejecting rejecting the user 'email address'.

Is it possible to see why these are being rejected? It looks as though the authentication has been successful on the RADIUS server.


  • Zyxel_Cooldia
    Zyxel_Cooldia Posts: 813  Zyxel Employee
    Hi @jw708,
    In authentication flow, USG-210 send access-request to Radius service for user authentication, and granted access if device receive Access-accept.
    The USG-210 will react accordingly based on the response from Radius server.
    In this case, you could check more detailed reject reason on Radius or MFA log for further diagnostic.
    Grant access case:

    Reject case:

  • CHS
    CHS Posts: 113  Ally Member
    You can check "login users" table in monitor page if any user ID is display as email address.
    If without email address listed in table, than log entry should be result. (rejected by RADIUS server)

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