Windows11 DHCP doesnt accept IP

The problem is with MS DHCP client in W11.

• The W11 DHCP client send DHCP-DISCOVER with Broadcast flag set to 0 (unicast):
• DHCP server receive discover and make DHCP-OFFER with Broadcast flag 0 and send reply directly to IP and specified mac address
• the W11 DHCP client or windows itself ignored this packet and make another DHCP-DISCOVER and so on
• after few tries (with ESET Antivirus installed it can take even 8 minutes.) the DHCP client sets Broadcast flag to 1 and send DHCP-DISCOVER
• the DHCP server make DHCP-OFFER with BR bit 1 and send to 255.255.255.255 and eventually the client "hear" this offer and make DHCP-REQUEST with BR flag to 1
• the DHCP server hear request and make DHCP-ACK with BR flag to 1 and send to 255.255.255.255
• the W11 client "hear" DHCP-ACK and use received IP

There are two working workarounds of this problem (choose one - suitable for You)

1. make DHCP server reply always with Broadcast bit 1 and send to broadcast address (255.255.255.255), when windows client is detected, in ISC DHCP server is like this:

      class "windows" {
      match if option vendor-class-identifier ~~ "^MSFT [0-9\.].*";
      always-broadcast on;
      }
   

or

1. change W11 dhcp client parameters to always use broadcast flags in Ethernet and Wi-Fi connections - it will work for newly installed network adapters

      Windows Registry Editor Version 5.00
      
      [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Dhcp\Parameters\DhcpGlobalForceBroadcastFlag\0]
      "9"=dword:00000001
      "14"=dword:00000001
      
   

2. Change DhcpConnForceBroadcastFlag for each installed network interfaces by doing this:

Find installed adapters in:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\NetworkCards

and write GUIDs

Use found GUIDs and (using found GUIDs) go to:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\$GUID

and set "DhcpConnForceBroadcastFlag" DWORD to 1 for each found GUID

Reboot Windows

Both solutions works independently of each other.

This might be a bit of necromancy in this thread but we've had exactly the same problem and we fixed it by removing an old option we had set on our domain range DHCP : 'option 33', a static route information that was pointing to a different range, used to be our old proxy, we didn't need it anymore so we simply deleted that option 33 part entirely.

Just a tad bit more information, our ranges are 10.* (not gonna spill much) with a /21 mask and the proxy was on a 192.168.4.* /24 (it's entirely gone so I don't mind). I don't know if this would play a role or not.

Hello.

Here are a few steps you can try to resolve the issue:

1. Check that your network adapter is set to obtain an IP address automatically. To do this, go to Settings > Network & Internet > Ethernet (or Wi-Fi) > Change adapter options. Right-click on your network adapter and select Properties. Make sure that "Obtain an IP address automatically" is selected under the IPv4 properties.
2. Check that your DHCP server is configured correctly. Make sure that it is configured to provide IP addresses in the correct range for your network, and that it is not running out of available addresses.
3. Try releasing and renewing your IP address manually. Open a command prompt and type "ipconfig /release" followed by "ipconfig /renew". This will release your current IP address and request a new one from the DHCP server.
4. If none of the above steps work, try resetting your TCP/IP stack. Open a command prompt and type "netsh int ip reset" followed by "netsh winsock reset". This will reset your network settings to their default values.

Best Regards,

Hania Lian

We had the same problem, after two months we found (now) the solution (I hope).

After update many PCs W11 to 24H2, the LAN controller don't take the IP from DHCP. We try all solution found on web, but no-one solved the problem (Update/Remove Driver, change registry, USB Ethernet, holy water, voodoo,...).

We have two Windows DHCP server in failover configuration with two different version of OS (2012 and 2022), everything works fine except the W11 24H2 clients.

After read David G's solution, we re-check the configurations, we don't use the 033 option, but we found the 043 option configurated (i don't know why we added this option)

We try to remove 043 option, run "Replicete Failover Scope..." and now works!!!

Found the solution! Go into device manager, expand network adapters, right click on your network driver, hit update driver, browse my computer, let me pick from available list and then look for the driver with ethernet in the name. Thats what worked for me and I hope it works for everyone else :)