@ShaunST My final fix: turn off the 5 Gz radio on the router. Everything now works flawlessly. Sacrificed that option because the USB 3.0 file sharing is too important to my needs.

@usoliveira It's working OK except for the witness lights, so I am letting sleeping dogs lie.

Disconnect from any VPN you might be using. Some sites will reject a connection thru known VPN IP addresses. I just connected to the Apollo Journal and Samsung sites thru my C9 V1. The Samsung site...

I have the same issue on one of 3 C9's. Only the USB LED will come on when I have something plugged in there, but otherwise no lights. Everything else works fine. Have learned just to live with it....

Had similar intermittent problems on C9 with 2.4 GHz clients dropping and having to be re-set completely. This is an issue not limited to TP Link... other mfgr forums have similar posts. If you can...

In the advanced network tab of your router setup, temporarily change the Primary DNS server to 8.8.8.8 (Google's public server) and re-try. If it works, the DNS cache of your original DNS server is...