@sadeyes 

Make sure extender is not connecting from a incorrect password.

Get your smart phone, and forget the Wi-Fi network you are trying to connect the extender to, now connect back so you are prompted for the password, enter the same password you put for the extender when setting it up in the Tether app.

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@Tony 

Hi, Thanks for the response.

It turns out my ISP did something to my host router that caused this problem.

It affected my wireless printer as well.

They had a system outage in my area and when that was resumed all was well again.

Printer back and the TP-Link extender back.

I'll never know what actually happened.

I do know my WiFi channel within the 2.4 Ghz band had change and then changed back.

All is well now. Thanks for the contact.

@sadeyes 

Wow, that is very odd.

Thanks for the update though!