Hold the wifi button for 10s to have a try.

Can you get IP address with wired connection from the extender? Is the Ethernet light on on the extender? Do you try different computers?

The firmware for powerline extenders has two part, one part is wired, one part is wireless. The bin file is wireless firmware, the NVM is wired firmware. It seems there is no wired firmware available...

What's the model of your powerline units? Do they have the same wifi name as your router? It's better to setup different names on them to have a test. What's the Wireless Channel on the powerline...

This one : TD-W8968_V2_150515

From the WAN info, you should have internet access, did you try hard reset the modem and reconfigure it? Did you contact your ISP? If still the same thing, try change the DNS server to 8.8.8.8 on the...