@Andy70 

Do you mean the Smart TV is tryig to connect the extended network but the network name displayed on the TV is different from the extender's actual network name?

If that is true, it must be a different network, please rescan the available wireless network and select the correct one.

In addition, please also try other client devices to see if they could see and connect the extended network properly.

If the extended network and your router network share the same wireless network name, you should just select your router network name to connect the WiFi.