@dtollst 

If you only have the power light then the extender did not connect to the router. Factory reset the extender by holding the reset while it is plugged in and set the device up again. I would recommend using Tether to do that: https://www.tp-link.com/us/support/faq/1373/

@Tony 

Only power LED solid for my extender device AC-750.

Reset the device by holding reset for more than 10 seconds with power connected. Set-it up with Tether app. Still no wifi connection.

Am I missing anything?

Thanks.