Conflicting IP address

[gafferlyons]

I have a MacBookPro (Mid 2012 Retina), a great machine. I fitted an AirPort Time Capsule 802.11ac 2TB. Up until recently it has worked very well, but now I get a message that there is another device using the same IP address as my MBP. This causes the MBP not to connect to the internet. If I disconnect the AirPort TC my MBP then connects to the internet.
Can I change the IP address on the AirPort TC?
I have no idea how this came about, because I do not know enough to change any IP address.
I need the AirPort TC for my backups.
Help
Thanks
Peter

 

[KevinJS]

I'd start off with every device that can connect to your network turned off, reboot your cable modem, followed by your TC, then each device, starting with your Mac, then phones, tablets and game consoles etc.

The reboot may take care of the issue, and if it doesn't you need to isolate the device that's causing the problem in any case, so it's probably the best place to start.

 

[Ember1205]

How MANY devices do you have connected to your network? It's possible that you have more than what the DHCP range can accommodate and something else has grabbed the IP your Mac wants and now your Mac can't get it.

Are any of the other devices on the network computers of any sort? If so, what about opening up the administration interface of the device doing DHCP (router?) and seeing what devices are connected with what IP addresses?

 

[KevinJS]

Most home networks default to 192.168.0.xxx. That allows 255 devices to connect.

I suspect the router should be (and isn't) in bridge mode with the ISP supplied modem handling DHCP. My ISP set up their modem in bridge mode for me so that my AirPort Extreme could control the network. A power outage reset the modem to DHCP mode and caused a conflict which I corrected by switching the Extreme to bridge mode.

But rebooting is often a quick fix, yielding results even if the cause of the problem was never found.

 

[pm-r]

Try this:
"“Another device on the network is using your computer’s IP address” Mac Error Fix"
http://osxdaily.com/2010/09/19/another-device-on-the-network-is-using-your-computers-ip-address/

 

[Ember1205]

Most home networks default to 192.168.0.xxx. That allows 255 devices to connect.

I suspect the router should be (and isn't) in bridge mode with the ISP supplied modem handling DHCP. My ISP set up their modem in bridge mode for me so that my AirPort Extreme could control the network. A power outage reset the modem to DHCP mode and caused a conflict which I corrected by switching the Extreme to bridge mode.

But rebooting is often a quick fix, yielding results even if the cause of the problem was never found.

Both of those statements are incorrect.

Firstly, MOST home network devices defaults to 192.168.1.xxx.

Secondly, there are 256 possible addresses that are available on that network. They are allocated as follows:

0 - Network address (special, reserved)
1 - The router's address, pre-configured
255 - Broadcast address (special, reserved)

That leaves 253 addresses that could potentially be used by other devices on the network.

 

[KevinJS]

OK. Corrections accepted. I got my 1 and 0 confused.

 

[lclev]

I would be willing to bet that your ISP's modem/router is handing out ip addresses as well as the TC for your wireless network.

Here is how I have my home network setup. I let my TC handle DHCP for my wireless network. I turned off the wireless feature on my ISP's modem/router but I let it hand out ip addresses to anything connected to it by ethernet cable which, in my case is only the TC. This allows me to communicate with both devices and both my macs can back up to the TC through the wireless connection.

If you are still having problems and would like to set your network up similar to mine or even some other way, post back and provide the name and model of your ISP router/modem plus any other setup particulars you have and I will try to help.

Lisa

 

[gafferlyons]

I tried most of the suggestions on this feed, but ended up talking to Apple support, Stephen. He tried all of the above with no success, but suggested I contact the ISP help line. This I did, we changed the IP address of the computer and the Airport Time Capsule manually and problem solved. I am very pleased.

 

[ferrarr]

Congrats for getting it all sorted out.

 

[pm-r]

I tried most of the suggestions on this feed, but ended up talking to Apple support, Stephen. He tried all of the above with no success, but suggested I contact the ISP help line. This I did, we changed the IP address of the computer and the Airport Time Capsule manually and problem solved. I am very pleased.

Glad you got things fixed and working, but mentioning earlier that you were also using static IP address would sure have helped provide a solution. A rather critical point with network problem solving.