@Ted53
Hello, please follow the instruction to log into the web page and tell me the current hardware and firmware version:
How to log into the web management page of the range extender
If the extender firmware is not the latest one, please update it first:
How to upgrade the firmware of my range extender
And then please reset and reconfigure it and check whether it works.
How to configure my Range Extender via Web GUI
Note: You can change the authentication type and encryption type of main router's wifi as AUTO.
If still failed, please relogin and show us the full screenshot of the status page. And please export the system to us which you can find on the settings-system tools-system log and please tell me the model number of the main router.
Thanks in advance, and have a great day.