AirPort and the stubborn cable modem
Just in time for the holidays, James Fillian attempts to express his thankfulness yet hits a wall. He writes:
I’m visiting my parents for the Thanksgiving holiday and want to use my MacBook and iPad in the spare bedroom. They have a wireless network but the signal doesn’t reach that room. I bought an AirPort Extreme Base Station, figuring it put out a stronger signal than the cheap wireless router they're currently using. I’ve connected it to their cable modem, run AirPort Utility on my MacBook (also connected to the Base Station with an Ethernet cable), and asked it to configure the Base Station for a DHCP connection, but it always comes up with a self-assigned IP address rather than the address assigned by their cable company. When I reconnect the old wireless router, it works perfectly. What am I doing wrong?
You need to reset the cable modem. How you go about it depends on the modem. In some cases you can simply unplug it, let it sit for a few minutes, plug its output into the Base Station’s WAN port, power on the modem, power on the Base Station, and then run AirPort Utility. With luck, the Base Station will pick up a usable IP address and be on its way.
However, some cable modems are reluctant to reset themselves this easily. They carry a backup battery that maintains the modem’s settings even when it’s unplugged—which is a good thing when you experience an unplanned power outage. If your parents' cable modem has such a battery, there’s a more-than-reasonable chance it also has a small reset button on the back. Flip it around and look for that button. If and when you find it, give it a firm push (you’ll probably need a paper clip or pen-point as these buttons are often resessed). This should allow the Base Station to pull in a working address.
No? Cable providers are often capable of resetting modems from their end. If nothing else works, give the provider’s tech support line a jingle and politely ask if they can do anything with the modem. When they come through, wish them a happy Thanksgiving. Even if they’re based far outside the U.S., they’ll appreciate the sentiment.