@dodge Hello, 

Kindly note that after they are paired in the same room (House led ON), locate the extender to another room, and it should work directly, do not need to press pair button any more at this moment May I know how many powerline unit do you have in total ? For the paring issue, it is recommended to  add extra powerline unit into existing powerline

https://www.tp-link.com/support/faq/1081/
 

Note:  press Pair button only for 1 sec, Power Leds should be flashing on both powerline units in pairing process. ( if the Power Led does not blink, press it for 1 sec again)
When the Powerline Led or House Leds are on, the pairing process is done.

@dodge  Hello, 

After the pairing process, the House Leds should be ON on the both units, that means 2 units are paired. 

If House Leds are ON on power line units , you could try some suggestions here:

0> wire tp-link main adapter to the main router via cable 
1> change a different Ethernet cable between Main router and main power line adapter
2> try a different LAN port on main router. 

If still the same problem,please connect a computer to router by Ethernet cable ( same cable that main powerline adapter is using) and check do you have any Internet? Please send us a photo of the IP address on PC when wired to router. 

How many Leds are ON on the main adapter and powerline extender? 
If connected to WPA4220 the wifi adapter by WiFi or by wire, what is the IP address & Gateway on your computer? https://www.tp-link.com/support/faq/838/