Does it only occur on the new Windows 10 PC? Also, check your TP-Link router's internet IP address as seen here. Make sure it isn't 192.168.x.x. Not that I think double NAT is causing this problem, but might be causing others.
192.168.0.1 apply to both the Cox and Tp-Link. Of course this confuses them and I can't get in.
That's a problem. You should disconnect the TP-Link from the gateway and log into the TP-Link and change it's access IP. See here on how.
I checked and the TP-Link Router is 192.168.100.1. Trying to connect to this gets the message it took to long to connect. I believe this is the default address for most routers and could be causing a conflict.
192.168.100.1 should only be the IP address of stand alone modems. Shouldn't cause a problem with a Cox gateway(which is 192.168.0.1). However, just in case, that is where unplugging the TP-Link from the rest of your network comes in. Either way, it's probably a wild goose chase. If you don't game or do anything advanced on your network, double NAT should be fine.
