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Posts: 2
Registered: ‎10-30-2011

The (in)famous IP address conflict...

Hi all


I have a linksys befw11s4, which seems to be working fine - the only problem is that every week or so, when more than two computers (or smart phones) try to connect  I get the "IP Address conflict" or two devices with the same IP address or " Wireless network connection doesn't have a valid IP configuration" ... there are thousands of similar posts on the internet, many with extremely difficult and complicated answers which seems not to work. This problem happens with computes/devices trying to connect thru wireless or thru lan cable. I tried fixing this so many times I don;t even remember when I started... I am extremely frustrated!!!


Is there any simple, one time solution? Upgrade? Software patch?


To me this seems crucial and very, very basic problem - if people at the end cannot connect, then all other features are worthless. It's like buying a new car which has a built in coffee maker and an excellent entertainment system but the engine will not start....


Hope anyone has some insights....



Posts: 490
Registered: ‎05-09-2011
Posts: 2
Registered: ‎10-30-2011

Re: The (in)famous IP address conflict...

Thank you, I will try your suggestion.


I checked my settings - it has "Obtain an IP address automatically" checked, which means the recommendation is to restart the computer every time there's an IP conflict.



Is there any way to fix this permanently without having to restart the computer every time? Will reinstalling the router driver help?

Posts: 5,369
Registered: ‎11-11-2008

Re: The (in)famous IP address conflict...

There is no driver for the router, only the wireless adapters.  Make sure all devices have DHCP set and not a static IP.

Posts: 490
Registered: ‎05-09-2011

Re: The (in)famous IP address conflict...

I'm not really sure which device is the culprit here as I've encountered this error countless times before. It could be how the computer obtains IP addresses or how the router hands out IP addresses but a sure fire way to resolve this is to assign static IP addresses on each computer on your network.

Posts: 7
Registered: ‎05-20-2007

Re: The (in)famous IP address conflict...

Though a manual IP address on any device can cause this, another common cause is this:


Your Linksys router probably has factory-default wireless settings and it's in-rage of a neighbor's wireless router with the same settings. Both routers see traffic that wasn't meant for it, and the wireless networks are "merged" in a way that causes IP conflicts.


SSID: linksys

Channel: 6

Security: none


...if these are your wireless settings, then this is probably the cause of your IP conflicts. You won't necessarily see two "linksys" networks when you look at wireless networks in-range.


Your router assigns local IPs to your devices starting with, ...101, ...102, ...103, etc. Each device on your LAN (local network) gets a slightly different IP address. Your neighbor's router does the same, also starting with When your router sees traffic that wasn't meant for it, it's extremely likely both of you have a device with the .100 address, and both of you will experience a conflict. If both of you have more than one device, you may also get conflicts from .101, .102, etc.


The popularity of Linksys-brand products makes this a common issue. However, I've had similar problems with Netgear, D-Link, and Belkin products. For a long time, the devices didn't have a unique SSID from the factory. It also would have made sense for each one to default to a setting that selects a random channel after every reboot (or scans and selects one with the least interference).


The solution is easy. Change the name and channel of your wireless network. That's also a good opportunity to enable WPA-Personal or WPA-PSK encryption and set a wireless password ("key" or "passphrase"). Make sure you use a wired connection when changing any wireless settings, or your computer can get VERY confused. Also keep in mind that your configuration password isn't the same thing as a wireless password. I would recommend writing down any passwords and keys on a sticky note and put it under your router. Usually, you want your household and guests to access this information, but strangers and neighbors won't be able to use your network without that information.


The merged networks present an unusual challenge. In the past, I have attempted to change the wireless settings by logging-in to the router's web configuration from a wired computer with no wireless capability. I rebooted the router and loaded the web configuration page at, then promptly changed the network name and channel. It turns out that traffic was already merged with the neighbor's router. Even though I used a wired connection, my changes were applied to the neighbor's router! My router still had an SSID of "linksys" and the neighbor's had the new SSID. The wireless networks were no longer merged because the SSIDs were now different, so I rebooted the router one more time and made my changes (making sure to use a *slightly* different SSID than the one that was applied to the neighbor's router). I used another wireless-capable computer to connect to the neighbor's wireless and undo those accidental changes.