Maximum PC

The router in question is a Belkin F6D4230-4 v. 1000 and belongs to a friend of mine who set the router up several months ago using only the setup disk that came with it. He has Cox Communication's Hi-Speed Internet access via an Arris telephony modem and set up the wireless router so that he could share a wired connection with his XBox 360 with his HP computer (which he purchased last December) with Windows 7 Home Premium as the OS. Yesterday, he emailed me for assistance telling me that his wireless router was "messed up". When I went over to his apartment to investigate the problem, I found that using the ipconfig utility in the command line revealed his default gateway to be an IP address which corresponded to the Arris modem, rather than the router's web interface address of 192.168.2.1. Also, he was unable to access the router's web interface at all, but was able to connect to the Internet via his computer, but unable to access the Internet with his XBox 360. All network connections between the computer's onboard Ethernet port, the modem, and the router were secure (as were the network cable connections between the router and the XBox 360). What bothered me the most were the references to some form of "tunnelling protocol" in the ipconfig utility. Two separate chat sessions with Belkin's support technicians finally yielded a solution in the form of a "hard reset" of the router (which involved not only pressing the well-hidden reset button with a paper clip, but unplugging the router while holding the reset button in for sixty seconds) and we were then able to access the router's web interface and adjust the router's security settings (which I believe were previously disabled in the owner's original setup as he didn't think they were necessary as he was not using anything in the way of a wireless connection to the router. Any ideas or thoughts as to what might have happened here? Thank you in advance for any and all helpful replies.

Sounds like he might have plugged his modem into one of the LAN ports. Perhaps his ISP gives him multiple IP addresses. Is he the one who originally set it up?

Yes, he originally set it up using the installation disk that came with the router. No, he followed the instructions carefully during the installation and plugged the Ethernet cable that connects to the Arris modem into the port on the back of the router that was labelled "modem". However, I believe that (because he did not have any need to set up the wireless security for the router) he left the wireless security settings disabled and I know for a fact that he had disabled the hardware firewall on the router (to speed up page loading in his browser). Also, he has never changed the password for accessing the router's web interface (the default is blank). I believe that someone accessed his router after seeing his SSID as an available network and, noticing that it was not secured, somehow set the router to use a tunnelling protocol to set up a secured wireless network connection for himself, yet without disturbing his ability to connect to the Internet with his desktop computer via the router.