In the last week I have experienced problems getting onto Xbox live. I have a wireless access point / router connected to a cable modem provided by my local ISP. After checking the settings on my router, it appears that the port for the xbox live service (3074) was producing outgoing traffic, but no incoming traffic. I don't have much experience with networking, but I suspect that whatever the ISP has on my modem is blocking incoming TCP packets on port 3074.
To test this, I plugged my laptop directly into the cable modem's Ethernet port and tried both Shield's Up! and Canyouseeme, both of which labeled port 3074 as closed. While plugged into the modem I also tried the following command,
hping3 --traceroute -V -S -p 3074 xbox.com
I received the following response,
using eth0, addr: X.X.X.X, MTU: 1500 HPING xbox.com (eth0 220.127.116.11): S set, 40 headers + 0 data bytes ^C --- xbox.com hping statistic --- 47 packets transmitted, 0 packets received, 100% packet loss round-trip min/avg/max = 0.0/0.0/0.0 ms
Is this the right way to find out if my problems are being caused by my ISP? I'd like to know before contacting my ISP.