Windows has detected an IP address conflict

CaptainPickard
CaptainPickard used Ask the Experts™
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On bootup of one of my home PCs, it says "Windows has detected an IP address conflict. More details are available in the Windows System Event Log" as the desktop matures. I looked my "whatismyip.com" and heck, ALL of my PCs have the same IP address. I'm trying to figure out why I can't see any of my IP cameras in the Network Video Recorder Software. They were working before.
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Most Valuable Expert 2015
Commented:
Whatismyip will give you the IP of the WAN part of your Router, and not the internal LAN IP's of the PC's. If you set all the internal devices to get their IP from your DHCP server (usually the router), and if you don't have more than one DHCP server running inside your LAN, you won't get assigned the same IP to different devices. If you need static IP's, then reserve them via your DHCP server, there you can normally assign an IP address to a specific MAC address. As these reservations usually notice when you try assigning the same IP to different devices, you shouldn't get the issue that way anymore. Apart from that, you have everything centrally organized and you won't have to setup every device manually.

Author

Commented:
I'm looking at the DHCP table in the router but I don't see any conflicts. I think the NVR has its own DHCP server...

ROUTER:
 ROUTER
Network Video Recorder:
 NVR
Most Valuable Expert 2015
Commented:
First of all make sure all the connected devices (PC's, IP Cameras etc.) are set to use DHCP (Automatic IP Configuration), then reboot them so they can acquire a new IP from your server. If any device is set for a static IP, and that IP happens to be used already, you'll get that issue. You won't see static IP's on the DHCP server unless you have set their reservation there, and not on the device itself. Also, it isn't very good practice to use the complete available IP range like in your example for the DHCP server. Leave some space available in case it is necessary to give a device a static IP. Change the starting address to something like 192.168.100.20, you'll probably still have more than enough addresses available for use.
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Gerwin Jansen, EE MVETopic Advisor
Most Valuable Expert 2016
Commented:
You should have only 1 DHCP server in your network or more than one but then they must server different ranges. For testing, disable DHCP on your NVR and let it get an IP address from your main DHCP server (your modem).
You will need to put your NVR on your router's 192.168.15.x network:
Change the LAN IP Address of the NVR to 192.168.15.x so that it will be accessible from your router's 192.168.15.x network.  Turn off the DVR's DHCP Server, and manually assign your cameras a 192.168.15.x addresses (if they're IP Cameras).  Or, you can let your router assign those IP addresses automatically.  What kind of software are you using to connect to your NVR?  You can probably go to your NVR's ip address from an internet browser (usually IE).

If you need your NVR accessible over the internet:
From your router, setup port forwarding to point which ever ports your NVR uses to forward those ports to the 192.168.15.x address you assigned it.  From there, you can access your NVR from your whatismyip address.
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I'm not sure why your computer is getting an IP conflict error. However, I would disable then enable your network adapter to reset things.  Or, open up a cmd line and type 'ipconfig /release' then 'ipconfig /renew'

Author

Commented:
The PC that is having the conflict is connected directly by ethernet to the DVR just like the cameras

Author

Commented:
Reporting the conflict I should say
Gerwin Jansen, EE MVETopic Advisor
Most Valuable Expert 2016
Commented:
What is the IP Address of the PC that is reporting the conflict? Start a command prompt and type "ipconfig /all" and post the results please. That PC is only connected to the DVR or has that PC 2 network interfaces? The IP camera's are connected to the DVR, right? What brand/type of DVR / IP camera's do you have?

Author

Commented:
Sigh...now I have a completely new problem. My internet connection is gone from the affected PC. The PC says it's both connected and disconnected. I clicked disconnect and reconnect but no change

 WTH?

Author

Commented:
Tried rebooting, Tried cold boot, tried "Diagnose"...
Commented:
A DVR, no matter what brand, is just another computer that runs video software for collecting video data. If you are directly connected to the DVR without going through the switch, you need to have a crossover cable for computer to computer communications.

A DVR is usuallya FIXED IP, so people can remote into i without trying to guess a dynamic IP. So, a fixed IP could be manually configured as the same IP as a dynamic IP by mistake, (hence causing an IP conflict). Also, this makes looking in the DHCP leases inconclusive because one is a fixed IP, not a DHCP lease.

Instead, look in your DNS Host A records. By default, nics send out UDP broadcasts to register within DNS. So, you can look at the host A records and see both a fixed IP and dynamic IP when they register. another means to check DNS is to type: Ping -a xxx.xxx.xxx.xxx (where xxx... is the IP of with the conflict). That will query the DNS records and send a ping to that computer of the first Host A record it sees. So, you have a 50/50 chance of finding the conflicting host.

OR... if you type the \\IPaddress\c$  within the network browser, you might be able to look at the C:\drive of that computer to see what's on the hard drive to help you determine what computer is conflicting. To see if it's a router or something with a web page interface, you can just type the IPaddress of the conflicting node. That would give you a web page, (like Linksys/Dlink/mass storage device) asking for logon credentials.

 

Author

Commented:
Odd, I turned of the DVR and got my internet connection back. My internet is wireless

Author

Commented:
Problem solved with a little help from all :)

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