Q: Received following message: "Another device on the network is using your computer's IP address(xxx.xxx.x.x). How do I determine the other device? How serious this problem? How do you change IP addresses?

Try disconnecting your router's power for at least one minute. The reconnect it. See if that helps.

Glad I could help.

<Edited by Host>

Most likely, you're getting a network address from your router. The address assignment ("lease") expires, and has to be renewed, after a certain amount of time, which might be one hour or one day. The lease expired without being renewed because the device was offline at the time. Meanwhile, the address was leased to another device on the network. When the first device comes back online, it still has the address that's now also leased to the second device. Depending on what kind of router you have, the conflict may resolve itself automatically. If not, then from the menu bar, select

           ▹ System Preferences ▹ Network

If the preference pane is locked, click the lock icon in the lower left corner and enter your password to unlock it. Then click the Advanced button and select the TCP/IP tab. Now look at the menu labeled Configure IPv4. If the selection in that menu is Using DHCP, click the button labeled Renew DHCP Lease. Test.

Less likely, you have a network address that you assigned yourself, and another device is assigning itself the same address. In that case, the selection in the Configure IPv4 menu will be either Manually or Using DHCP with manual address. This kind of conflict won't be resolved automatically. You have the following options to resolve it:

1. Change the menu selection to Using DHCP.
2. Change the manually-assigned address to one that isn't being used by another device.
3. Change the address of the other device.

Which of these options you should choose depends on the details of why you're using a static IP address. Any change you make to the network settings must be applied before it takes effect. To do that, click OK and then Apply.

That's because the DHCP lease was renewed.

Hi Linc

I have exactly the same problem, it only occurs with my laptop and one of the many other devices in our home, but I don't know which.  I can confirm that my laptop is set to Using DCHP.  It also recurs regularly and has been for several months, and I can't pinpoint the addition of any device that might have trigger it.  It is easily fixed by restarting the airport base station, but I don't think I should have to. I haven't tried manually establishing an IP address for my laptop to date as I don't know what number might be available.

When it occurs next should I work my way around all of the devices to determine which one is causing the problem and then check it is set to automatic and not manual as well. Or is there a better solution? I hope this makes sense and that it's not rude to ask a question on someone else's discussion.

Regards

Shane

If you have an Airport Extreme, it is very simple to configure IP address leases for each of your devices.

You'll need to know the Mac address of the interface that it is connected with (WiFi or Ethernet).

Edit the Base Station configuration in Airport Utility and select the Network tab.

Under the DHCP Reservations list box, click the + button to add a new Reservation. Enter the details for each device. Then, when each of those devices connect, they will always be assigned the same address and you will have no conflicts.

Hi

I haven't taken your advice yet because I investigated matter further.  I got a wifi scanner from the App store installed that to our iMac and scanned all of the devices on our wifi system.  That identified everything I expected and nothing extra.  It also identified all of the IP and MAC addresses for the 12 devices so it was quite handy.

The key factor is that when my laptop shows the message "Another device on the network is using your computer's IP address (xxx.xxx.x.xx)", there is no other device actually using that IP address.  I've repeated this a few times as the problem seems to be getting more regular.  So that makes me wonder whether the cause of the problem is something different e.g. some type of hardware failure. It is an early 2011 model.  Although since replacing the memory and the battery it still goes like a new one.

The other aspect here is that my MBP is the only device that has this problem.

Your thoughts?

The key factor is that when my laptop shows the message "Another device on the network is using your computer's IP address (xxx.xxx.x.xx)", there is no other device actually using that IP address. 

Yes, you are correct. As a matter of fact, it is almost always such that no other device is actually using the IP address. It is a function of errors in the DHCP process that result in the error dialogs you see.

If you configure your AEBS as I described, you will never see those errors.

Woke up and saw this message on my laptop at 1 am tonight, and wondered if my neighbor's kids (computer nerds) were up to something...

But one of my kids then came up from the living room, told me the fuses had blown three times - which includes the fuse that the WIFI is on.

He'd connected a new electrical heater in the room, which blew the fuse whenever the other electrical heater in the same room switched on.

... Or so I think, after searching the net on the topic.

Thank you, this fix is great and worked very well. Thank you for being able to help, much appreciated.