My wife extender AC750 is not connecting to my smart TVs???

@Delux 

Look at the LED lights on the extender, if the LED lights indicate it is connected to your router then what is likely happening is the extender is broadcasting the same network name of your router.

If that is the case, then stay connected to your original wireless network.

If you notice the signal is weak, when you are around your extender, then I would reconfigure the extender to have a different network name.

You could use Tether for that: https://www.tp-link.com/us/support/faq/1373/