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I have always been able to use my iBook (with AirPort) at my boyfriend's house flawlessly. They have cable internet with a Linksys router. Today I was upstairs browsing the net fine for hours. Closed the book, took it downstairs, opened it again, and even though my AirPort signal was strong and it said I was connected to the linksys network, Safari, Mail, & Adium refuse to acknowledge an internet connection. Network diagnostics said server, isp, and internet failed. I didn't change any settings at all. All other computers in the house can use the internet fine. I cannot figure out why all of a sudden these programs won't see the internet, when AirPort says I am connected with full signal. Any advice?

[ghporter]

Have you thought of simply restarting the computer? Sometimes a "lost connection" is just a "forgotten connection," and restarting the computer puts everything right.

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Originally Posted by ghporter

Have you thought of simply restarting the computer? Sometimes a "lost connection" is just a "forgotten connection," and restarting the computer puts everything right.

I turned the computer off and on (not restart) and also turned the AirPort card off and on several times to no avail. I finally looked in Sys Prefs in the Network pane. It shows that AirPort is connected but has assigned it's own IP address and therefore may not be able to connect to the internet. This makes no sense to me as literally less than five minutes before the internet stopped, I was using it just fine. I was upstairs using it, closed it to bring it downstairs, opened it up and no internet. It works nowhere in the house now. But everyone else's computer does.

I'm at home now with my AirPort base station and DSL connection and all is fine.

[ghporter]

There are a number of things that could be happening. If the network router got stupid, it could forget which hardware had which IP and that would certainly wipe out your connection, whether the wireless part was working or not. (That takes a simple power cycle on the router to "un-dumb" it.) Some people have experienced a variety of situations that all boil down to their AirPort card not waking up properly, but as you disabled and enabled the card several times, that's probably not it. Again, a restart of the computer is usually your best bet for correcting this sort of "everybody's but mine works" situation, particularly if you've already done other things like power cycling the router.

[webcookie]

Thank you, ghporter, for that response. I will ask my boyfriend's dad to reset the router. I've already turned my computer off and on and that did not change the situation. Two desktops and one laptop (all Windows) in the house work fine with the internet. The network pane in sys prefs said I'm connected to the network just fine but that AirPort has a self-assigned IP address and may not be able to connect to the internet. Which makes no sense to me as it has always been that way and always connected.

[ghporter]

The issue gets confusing sometimes because of how DHCP works. It assigns IP addresses automatically (on request from a properly configured network card) and for a particular length of time. This is called an "IP lease." It's typical for a home router to have particularly long IP lease times, sometimes days or even weeks. Now, if your computer decides that its lease has expired, it will give up that IP and request another, which is what it should do. But... it's quite possible the router's DHCP server to get stupid and stop issuing IPs, and while this keeps you from getting a new IP lease, the other users with unexpired leases do not see anything wrong and won't until their leases expire.

The easiest way to see if this is happening is to go to the Network Preferences pane and select your connection (in this case your AirPort card), then click on the "renew IP lease" button. If it fails, but the computer next to you still has a connection, it's probably (almost certainly) the DHCP server that's at fault. Most home routers don't have separate controls for their DHCP server, so you basically have to reboot the whole router to restart it. This is no big deal because it should only take a minute or two for everything to settle down-and get your connection working again.