Your TP-LINK kit is in a different powerline network as powerlinks, right? How about status of all lights on TL-PA4010 and TL-WPA4220? Did you pair them and make them communicate with each other?

What's your operating system? Try to follow the guide as below. http://www.tp-link.com/en/article/?faqid=306

So strange...I suggest upgrading latest firmware, reset it to factory defaults and reconfigure it.

Select a Log Host first and Index of the first will change to the one you selected. Enable it and you will be able to enter a Host IP. Apple it and Save configure.

What IP address? Screenshot please. Any other network device connected to SF1008D?

I refer to wireless channel which can be modified to ensure a stable connection. On its web interface, you can go to Interface Setup---Wireless to change it to 1, 6 or 11.