No doubt, technical errors or the wrong information can cause you to face Linksys extender login errors for sure. Unfortunately, being a non-technical person, it might be difficult for you to resolve those login issues. In that case, you will be required to use some troubleshooting tips after identifying the sources of the errors. So, check the extender’s working first whether it is capable of performing the process or not. This includes checking the power supply, networking your device again if that is not connected well, and verifying the web/IP address that you are using currently. 

If still, the error keeps occurring after checking those above-mentioned points, then reboot the extender once. Discard the extender from the power socket and leave it discarded for some time. Later, plug it in again into the same outlet and turn the switch on as well. Check the LED indication and try performing the login process from the web portal or through the WiFi app. If you are successful in that process, it means the actual problem was in the power socket rather than in the extender’s information. But, keep in mind to use those consideration points while logging into the extender.