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may be helpful:
Panther is losing a supplied DHCP address
Mac OS X v. 10.3 � Panther � is a rock-solid, easy to use operating system that provides you with innovative network features.
Under some very rare circumstances, it may "lose" the DHCP address that your AirPort base station is attributing to your computer.
However, don't worry ! This minor "issue" is really easy to fix and this FAQ tries provides you with step-by-step instructions.
Indeed, the easiest way to solve it is to uncheck the "Distribute IP addresses" in the AirPort Base Station.
In order to do so, follow these steps :
Disconnect the AirPort base station from your Local Area Network and connect it directly to your Mac by using an Ethernet cable. Note that you should plug the cable into the "LAN" port of the base station. There is a small logo that looks like an arrow right next to it.
Launch the "AirPort Admin Utility", located in your "Utilities" folder.
Select the base station in the list that appears and click on "Configure". You will be asked to enter the base station password.
Click on the "Show all settings button"
Click on the "Network" tab
Uncheck "Distribute IP addresses
Click on the "Update" button to upload your new settings to the AirPort base station
You can now reconnect the AirPort base station to your network, as it was before
Note that you will not lose any functionality on your network. Indeed, for this "issue" to occur, another device must already be distributing the IP addresses. This is just a matter of how the network is set up.
Troubleshooting tip :
In some cases, the AirPort base station may not appear in the AirPort Utility. This is however very easy to solve.
Indeed, this just means that the "Network" port has been disabled in the "Network" preferences pane, available through the "System Preferences" application.
Just open it and use the "Show" pop-up menu to see the "Network Port Configuration". Then, uncheck "AirPort" and check "Built-In Ethernet". Click on "Apple Now" to save your settings.
Once you have changed the settings of the base station, follow the same steps to revert to your original configuration.