I have a TP-Link TD W8970 modem/router. Just for fun i tried to perform a port scan on it. I found this:
$ nmap -p 1-65535 -n 192.168.1.1
Starting Nmap 6.00 ( http://nmap.org ) at 2016-01-21 16:17 CET
Nmap scan report for 192.168.1.1
Host is up (0.0097s latency).
Not shown: 65530 closed ports
PORT STATE SERVICE
23/tcp open telnet
80/tcp open http
1900/tcp open upnp
7547/tcp open unknown
50393/tcp open unknown
Nmap done: 1 IP address (1 host up) scanned in 54.03 seconds
Aside from ports 23 80 1900 (even though i have upnp disabled), what about the other ports?