Sounds good - the screenshot of the Status page from the router will tell a lot.
The IP of the modem is 192.168.100.1, and the IP of the router is 192.168.15.1. The fact when you are connected to the router you can access the modem means it is possible the WAN IP of the router is 192.168.100.xxx - which would mean you have a router behind a router (aka Double NAT).
The 73.39.xx.xx IP you reported above, did you find in that in the D-Link router interface or the TP-Link modem interface?