Troubleshooting logins (Auth Log reasons)

Every login attempt is in Auth Log with its exact reason:

Invalid voucher / username - code does not exist on this site (check the site and code type).
Device limit reached - the code is bound to another phone; press Release device.
Voucher has expired / Time quota used up / Data quota used up - add time or data, or sell a new plan.
Too many wrong codes - the device is locked for 15 minutes.
Unknown NAS - the router is not registered or its identity / IP changed.
Bad Message-Authenticator - the shared secret on the router does not match.
Service suspended - the subscription of this account is not active.

Use the RADIUS Tester to check any code against the same rules.