If you've ever seen a "Windows has detected an IP address conflict" or "another computer on this network has the same IP address" message, you might wonder what this warning means. While IP conflict issues aren't usually difficult to fix, they are confusing, especially for those new to networking.
Let's look at what an IP address conflict is, whether two devices can have the same IP address, and how to resolve this error when it pops up.
What Is an IP Address Conflict?
An IP address conflict occurs when two or more devices on the same network are assigned the same IP address. To explain why this is a problem, we must take a step back and look at what IP addresses are for.
Like a physical home address for receiving mail, IP addresses act as a way to identify your computer on a network. Your router uses those IP addresses to direct network traffic to the right devices. Check out our explanation of how routers work for more details on this.
Because of this setup, no two devices on one network can have the same IP address. If this happens, the network becomes confused by the duplicate IP addresses and can't use them correctly. Think about mail delivery trying to find the right mailbox if two houses on the same street had the same number; it's the same way for your home network.
Keep in mind that we're only talking about private IP addresses here, which refer to addresses used on your own network. Public IPs are how the rest of the internet sees any device on your network, but they aren't relevant to this discussion about duplicate IP conflicts.
How Does an IP Address Conflict Happen?
Since two computers cannot have the same IP address, how does the duplicate IP error occur? Under most circ*mstances, in modern home networks, IP conflicts are rare. This is because of DHCP (Dynamic Host Configuration Protocol), a system that routers use to hand out IP addresses.
With DHCP, when you connect a new device to your network, your router chooses an available IP address from the pool of options. The device uses this IP for some time until the lease expires, at which point it has to get a new IP from the router.
Unless your router malfunctions, two devices should never get the same IP address under this system. Your router knows which IP addresses are already in use and won't give them out twice.
Thus, an IP conflict most commonly occurs when you assign static IP addresses on your network. Instead of DHCP automatically choosing an address for all devices, a static IP lets you specify a certain IP address that a network device will always use.
If you mistakenly assign the same static address to two devices, you'll run into a duplicate IP error. This problem can also arise if you set a device to use a static IP without reserving that address in your router. Eventually, your router will try to hand out that address to another device, creating an IP conflict.
Another IP conflict scenario can occur if you have two DHCP servers on your network (which you should avoid). For example, you might have your own wireless router connected to your ISP's modem and router combo. If both devices are acting as a router, they might hand out duplicate IP addresses.
Finally, you can potentially introduce duplicate IPs onto your network when a machine comes back online after being in standby mode.
For instance, say you leave your laptop in a hibernated state for two weeks. During that time, your router may revoke the laptop's IP address and assign it to another device, like your phone. When you turn the laptop back on, your computer might think it still owns that IP address, which results in an IP conflict with your phone.
This could also occur if you put your computer in standby mode on another network that uses the same IP pool as yours, then bring it home and reconnect to your network. If that IP is already in use on your network, you'll see an IP conflict error.
How to Fix IP Address Conflicts
Like all home network troubleshooting, the first step you should take to fix duplicate IP problems is restarting the affected computer and your networking equipment.
The IP address error could have been a small glitch, which a reboot will resolve. Restarting your router and modem (if they're separate devices) will re-assign all IP addresses via DHCP.
If restarting everything doesn't work, the problem is a little deeper. You should next check to see if your computer is using a static IP address.
Troubleshooting Duplicate IP Addresses on Windows
To check your IP settings on Windows 10, open Settings and go to Network & Internet > Status. Click Change adapter options on this menu, then double-click the name of your network connection in the resulting window. This process will take you through a few different dialog boxes.
In the Status window, click Properties, followed by double-clicking Internet Protocol Version 4. This menu should have Obtain an IP address automatically selected. If there's a manual IP address listed, select the automatic option instead and hit OK.
Repeat these steps for Internet Protocol Version 6 (if applicable) and see if the conflict goes away.
On Windows 11, you'll find these options under Settings > Network & internet. Select Ethernet or Wi-Fi depending on what kind of connection you're using, then click your network name to show more options. Click Edit next to IP assignment if it's not already set to Automatic (DHCP), then change it back to this.
No matter your version of Windows, you should also try releasing your computer's current IP address and obtaining a new one. Restarting does this too, but it's still worth a try at this time. To do so, right-click on the Start button (or hit Win + X) and select Command Prompt, Windows PowerShell, or Windows Terminal.
In the terminal window, type the following command to give up your current IP, followed by Enter:
ipconfig /release After this, use the following command to obtain a new IP address from the router:
ipconfig /renew This process should resolve any IP collisions by removing the duplicated IP address from one of the affected devices.
Troubleshooting IP Conflicts on a Mac
On a Mac, you'll find IP address options under the Apple menu > System Settings > Network. Select the connection type you're using, then click Advanced.
On the resulting page, select the TCP/IP tab. If the Configure IPv4 box is set to Manually, change it to Using DHCP. Check that Configure IPv6 is also set to Automatically (if it's not disabled), then hit OK.
To refresh your current IP on a Mac, click the Renew DHCP Lease button that appears at the right of this page.
Check Your Router for IP Address Conflicts
If the above steps didn't fix the duplicate IP issue on your network, you should next log into your router's administration panel and take a look at the connected devices. How you do this will depend on your router model, so we can't give exact instructions for each case. Have a look at our router management intro guide for help understanding the interface.
Typically, you'll find a list of connected devices under a section titled Attached Devices, Connected Devices, My Network, or similar. Have a look at each device and keep an eye out for duplicate IP addresses.
To help narrow this down, you can check the IP address of your computer by typing ipconfig into a Windows Command Prompt/PowerShell/Windows Terminal window or ifconfig into the Mac terminal. Then you'll know the IP address that's being duplicated, making it easy to look for in the list.
If you find two devices with the same address, remove any static IP address settings, or refresh their IPs in your router to resolve the conflict.
In general, you shouldn't need to worry about static IPs in simple home networks, so it's best to let your router handle all this. If you do need to reserve an IP address for some reason, make sure it's set in your router so it doesn't hand out a duplicate.
Show Which MAC Address Is Mapped to an IP Address
In case you're having a hard time tracking down one of the devices with a duplicate IP, you can check which MAC address is mapped to any certain IP address on your network. While the simplest way to do this is using a free tool like Advanced IP Scanner, you can use the ARP (Address Resolution Protocol) command to do it manually.
Open a Command Prompt, then perform the following:
- Type ping [IP address] to establish a connection with the device you're trying to track down.
- Once it completes, type arp -a to show the IP and MAC address info of all devices your PC has a connection with.
- You should see the IP you just entered, along with its MAC address next to it.
Update Your Router Firmware
A faulty router can cause IP conflicts to occur more frequently and without warning. If you continue to have IP address errors even after performing the above troubleshooting, you should update your router's firmware.
The exact steps to this also depend on the router you have. Usually, you'll find a Firmware Update option when you log into your router's admin panel. This may be under an Advanced or Tools menu.
While some routers let you update the firmware automatically through the management panel, others require you to download a file from the manufacturer and upload it to your router. Check your router manufacturer's website for more help if needed.
Resolve IP Address Conflicts Peacefully
Now you know what an IP address conflict is, how two devices could get the same IP address, and how to fix duplicate IP conflicts. Most of the time, a conflict won't occur on your home network unless you've messed around with static IP options. And if a duplicate IP problem does arise, you can usually resolve it by setting all devices to use DHCP and renewing their IP leases.
To go deeper into home networking, you should also understand MAC addresses and how they work with IP addresses.
