A common reason for getting CHAP authentication failed messages on your router is wrong settings. Especially after a power-surge which can cause routers to lose their settings.
Check your username and password on the router are correct and that the username has not been reset back to factory defaults.
Ensure the router settings are also correct.
Try the following test logins. Please note neither will provide full internet access but your router should show as connected and retrieve an IP address.
On Network (LLU):
Off Network (BT Wholesale):
Password: leave unchanged”
If none of the logins work, please try another router on the line or try the router on another line to ensure that the router is working ok. Otherwise please contact Technical Support and inform them you have completed all of the above .
4. Test your router on another broadband (ADSL) line to see if it can gain a connection or test another ADSL router on your line to ensure that the router is working correctly.
If none of these tests are able to restore your connection then please contact Technical Support in order to progress your issue.