Q: Another device on the network is using your computers IP Address. If you continue to have problems, change the IP Address of this computer!?

On each Mac, select  ▹ System Preferences ▹ Network ▹ Advanced ▹ TCP/IP. What values are shown for the following:

Configure IPv4

IPv4 Address

Subnet Mask

Router

Configure IPv4 - Using DHCP with manual address

Change that to "Using DHCP." Apply the change and close the window.

What that means is you were forcing your Mac Pro to always use the network address 192.168.1.67 since yo had manually assigned that. Normally this would be fine, your router would check for active addresses in use and assign a different address to any computers trying to join the network. The problem could arrise if your Mac Pro is off-line and the router had already assigned 192.168.1.67 to one of your other computers. When you tried to log in with your Mac Pro you would get the addressing conflict that you noticed.

Setting all computers to using DHCP will let the router handle the addressing.

I would check all of your computers and PC's. 67 is far enough in the middle of the range that I am surprised if the DHCP had handed that out to any client computer. You may have more than one of your computers set to manually assigned address using that same address. Make sure you set all of them to DHCP only. Also, check if you have any other IP devices like a printer or NAS drive that is using static addressing. Those can cause the same issues. I prefer to use static addressing with those as it makes it easier to find them on the network and since they are pretty much always left on the router knows they are there.

Linc, forgive the unrelated post. But I just wanted to personally thank you. You've helped with so many issues of mine with your solutions!

Glad to oblige.

Linc Davis | hyperrational • info

Linc,  I'm having same problem. my settings show

configure IPv4: using dhcp

Ipv4 address: 10.211.55.2

subnet mask: 255.255.255.0

router: (nothing here)

any help would be appreciated

thanks

Travis

Linc, I have the same issue.  This happened about a year ago and was thought to be a modem/router issue.  I switched to Airport and all had been fine until about a week ago.  Adding a note as my settings are slightly different from tsatterca1's above.  Setting are:

Configure IPv4:  Using DHCP

IPv4 Address:  192.168.1.84

Subnet Mask:  255.255.255.0

Router:  192.168.1.254

Configure IPv6:  Off

Any help would be appreciated.

Hi! I had the same issue. One day when I got home i had the same warning. After that everything is messed up. Please help me. Im no techy. I barely understand the conversation. But I really need help to resolve this. I have tried resetting the password of my router but nothing has changed. Both our phones arent able to connect to wifi, they recognised it but wont connect. Also, apologies for my ignorance but could my computer be hacked because of it? I suddenly need to log-in to facebook and other apps that I didnt eve log-out. Im really scared now. I dont know what to do. Please help me Sir.

I've just recently begun having the same problem, but under different circumstances. I thought I would describe my problem before I manually change the IP address, in case it is a larger problem:

About three weeks ago, I installed a SSD into my 2011 MacMini. I followed directions online to run the SSD and original HD as a Fusion Drive (I'm not completely convinced this setup is working exactly like an Apple-installed Fusion Drive, but it does show as a single drive, is noticably faster, and I haven't had any issues, so I am content with it for now). About a week later, I got the message about another device on the network using my computer's IP Address on the login screen after waking. When I logged in, I noticed it was not connected to the wi-fi, but I was able to connect by selecting my network. When I got the message again, I did some digging and found that the name for the mini on my network changed sporadically from MACMINI-587E6A to the 12-digit MAC Adress. I will occasionally be kicked off the wi-fi, but it connects again quickly. Both named devices use the same IP address, obviously. I've tried turning everything off and back on, but I'm still having the same issues. The mini is set to use DHCP, and I am not having issues with any other devices (Apple TV, iPad, Wii)

I guess my concern is that I've mixed something up somewhere, and the old and new configurations are both trying to connect and causing conflicts. Could it make it worse by changing one (or both) of the IP addreses? Does anyone know why it might be seen as two seperate devices?

Any advice or opinions would be much appreciated!

Thanks,

David

For those of you with wonky wireless issues try the following settings:

1. Network / TCP/IP - Configure IPv6:  set to 'Automatically'

2. Network / TCP/IP - Click on 'Renew DHCP Lease'.

3. Confirgure IPv4: set to 'Using DHCP'

In my house network we have 2  x MacBook Pros, 2 x iMacs, 2 x iPhones (4s and a 5),

1 x iPad2 and 1 Epson Wireless Printer.

We are running an old school Linksys Router '82.111G'.

I haven't had any ip issues - until we updated the

iPhones and iPads to IOS7. Then the 'using the

same IP address' warning popped up on our iMacs

a few times. I fixed it by using #2 above.

Papanate

Hello Linc , 

I live in a dorm for University and my macbook air (med 2013 ) is connected to it  like other students in dorm ...and  the macbook Air shows  a message that another device is using my computer  IP address . I don't have another device how to fix this and can people( in the dorm ) see my contents of computer ? such as pictures ,files and videos ?

my settings show

configure ipv4 : using DHCP

thank you so much i would appreciate your help .

sincerely ,

Ameer