Duplicate IP Addresses

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Level 1

32 points

Duplicate IP Addresses

I use a MacMini as a server and basically it's on all the time, so that's why this probably affects this machine the most. It'll loose internet communications with an error that it is sharing the same IP address as another device on my network. The device is always my Time Capsule. I use DHCP addressing this is AT&T U-Verse which supplies this through a 2-Wire gateway.

The solution for me it to open the AirPort Utility and reset the Time Capsule. Then the server is assigned a non-competing IP address. I've gone through the settings on the 2-Wire gateway to look at the IP distribution. The Time Capsule always seems to be assigned xxx.xxx.x.74, so I tried to "fix" the address to another address that is open within the range. Eventually, the MacMini also ends up with the xxx.xxx.x.74 same as the Time Capsule thus the conflict.

What sets off this addressing event?

MacBook Pro, Mac OS X (10.6.7)

Posted on Jul 8, 2011 10:50 AM

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Answer 1

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Eric Ross

Level 6

11,807 points

Jul 8, 2011 11:05 AM in response to razzman

How about setting your MacMini with a static IP address and set that DHCP distribution on your route to exclude that address. I am not sure how to do that on an AT&T system (i use cable) but I am sure you can check online for more information on how to do it.

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Answer 2

Aug 4, 2011 7:30 AM in response to razzman

I'm chiming in with a similar problem, but sadly, not a solution. I also have U-verse and a 2-wire gateway. However, I have an Ethernet switch behind the gateway, and 10+ "devices" on the LAN. 5 Macs, 4 iPhones, and an iPad. Plus Wii, a Femtocell, and various U-verse STBs. This network has been working well for over a year and until about June of this year, then my son's Intel iMac started popping up with this "duplicate IP" error - typically when waking up from sleep. I turned off his Airport and removed it from the network configuration, but that was not the issue. I didn't troubleshoot it very seriously, thinking he had somehow hosed up his machine. Power cycling the network (gateway and Ethernet switch) did mange to clear up the problem sometimes for a short while. This morning, however, the same error popped up on my Intel iMac for the first time. I went to the 2-wire management web portal and it did not show another device using the "duplicate." I also tried shutting down the iMac and "pinging" it's address from another machine. No ping replies - which means it's not another Mac, it *could* be one of the appliance-devices that isn't responding to ping, but I suspect that the iMacs are just getting confused about a non-existant duplicate IP. Thanks for any help you can provide.

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