Cannot access internet on a network on Windows XP when Windows 7 goes to sleep

Original Title: Windows 7  Windows XP networking problem.

I replaced a Windows XP computer on my 4 node (2 PC, 2 printer) wired network with a Windows 7 computer.  When the Windows 7 computer goes into sleep mode the other computer (XP) is unable to access the internet.  A message pops up that there are 2 computers with the same IP address.  If I wake up the 7 computer all is well.  What's up?  I am not sharing any files between the computers.



This typically happens when, for example, a router is switched off but one or more of the devices attached to the router is left switched on.

The devices retain the ip address allocated to them but when the router gets started up again it has no knowledge of this. So when you start up one of the other devices, the router may allocate an ip address already in use. Actual example that I reproduced with my router and PCs...

  • Boot router, then boot PC1 and PC2 - the router ( will allocate to PC1 and to PC2
  • Switch off the router, then switch off PC2, restart it and switch it off again
  • Put PC1 to sleep
  • Boot the router and PC2, the router has no knowledge of PC1 and will allocate to PC2
  • Wake up PC1 and it still has which is now a clash with PC2

Other ways of reproducing this situation may also be possible.

All devices on your network must have unique ip addresses, hence the warning message.

If you get this situation again, the solution is to switch off all devices including the router, then restart the router, then restart all devices attached to the router.

To prevent this, you may be able to set ip address reservations in your router which will ensure that all devices attached to the router always get the same (unique) ip address. If you don't know how to do this we will need your router brand and model to assist.


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Question Info

Last updated March 26, 2018 Views 326 Applies to: