Windows Vista can’t get an IP address from certain routers or DHCP servers

Applies to: Windows Vista BusinessWindows Vista EnterpriseWindows Vista Home Basic

Certain routers or DHCP servers are incompatible with Windows Vista. This article helps you resolve the issue. If you are not sure if your router is compatible, you can still try the fix.

Fix it automatically

Click "Fix this problem" to automatically fix this issue. Click Run in the File Download dialog box, and then follow the steps in the Fix it wizard.

  • This wizard may be only in English. However, the automatic fix also works for other language versions of Windows.
  • If you are not on the computer that has the problem, save the Fix it solution to a flash drive or a CD, and then run it on the computer that has the problem.


By default, the BROADCAST flag in DHCP discovery packets is enabled in Windows Vista (DhcpConnEnableBcastFlagToggle = 1). Therefore, Windows Vista gets an IP address by using the BROADCAST flag in DHCP discovery packets. If a router or DHCP server can’t process the DHCP discovery packets, Windows Vista will fail to get an IP address. The fix disables the BROADCAST flag by setting DhcpConnEnableBcastFlagToggle to 0.

By default, this problem does not exist in Windows XP Service Pack 2, Windows XP Service Pack 3 or Windows 7 because the BROADCAST flag is disabled (DhcpConnEnableBcastFlagToggle = 0).

More Information

If you know the router or the non-Microsoft DHCP server does not support the DHCP BROADCAST flag, you can configure the following values for the following registry entry instead of using the DhcpConnEnableBcastFlagToggle registry key. 
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\{<Network Adapter GUID>}

Value name: DhcpConnForceBroadcastFlag
Value type: REG_DWORD
Value data: 0
  • A value of 0 disables the registry entry. You can use this value to prevent Windows Vista from using the DHCP BROADCAST flag. After you configure the registry entry, Windows Vista never uses the DHCP BROADCAST flag.
  • This issue does not occur in Windows 7. By default, DhcpConnEnableBcastFlagToggle is set to 1.