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All my Windows 7 Enterprise Edition 64bit laptops have now failed to get an IP address from DHCP via either a wired or wireless connection. The majority of these machines are Dell Latitude 1545 but Latitude D520/530s are also affected. I have been able to resolve connectivity on the wired network by doing the following but it is also not reliable.

  1. Set the service to run under Network Service, restart it (it fails), set it back to Local Service and restart again.

  2. Set a manual IP address in the right range, it then connects and identifies the network successfully, the network adapter can then be set to DHCP and it will get an IP address correctly.

This is not persisted after a reboot.

THe wireless interface is able to connect correctly to the WLAN but cannot get an IP address, if a static address is set it is able to send and receive traffic but DHCP fails. The fix above does not work for any of the WLAN devices affected.

DHCP is from a variety of sources, a LInksys Wireless Router (WRT54G) and a Windows Server 2003 R2 DHCP server, they were working initially but stopped. Other devices are working fine (Macbook pro, iPhones, HTC, linux laptops etc)

I'm at my wits end as I am the only sysadmin at present and cannot afford the time to rebuild 8 or so laptops.

Thanks

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Would it be possible to confirm that during testing of DHCP there was only one device acting as the server at once? When you say they dont get an IP address we are assuming they get the 169.254.x.x address? It would be worth checking the Advanced Windows firewall to ensure it is not blocking DHCP. When talking about the services are you talking about the DHCP client service? - on the back of this are there any event log errors on both the server or the client win 7 machine? –  JamesK Aug 11 '10 at 12:49
    
Yes, they are getting a 169 address. I need to make an edit and declare that these are separate, physically discrete networks Need to check the logs to see the exact error, but there was one. A drivers update fixed it on one machine, need to test on the others. –  Dan Aug 11 '10 at 13:43
    
So the clients are on a different network from the DHCP server(s)? If so, what mechanism\device is forwarding DHCP broadcasts from one network to the other? –  joeqwerty Aug 11 '10 at 16:13

2 Answers 2

My understanding has always been that the Windows DHCP service will shut itself down if it detects the presence of another DHCP server on the network. As a first step, I would suggest shutting down the Linksys DHCP component and using only the W2K3R2 server as the DHCP server. Make sure the server and scope are configured correctly and reboot one of the affected client computers and see what happens. In addition, you can install and run a packet capture program on the DHCP server (and client if needed) and capture network traffic to see what DHCP traffic is being receieved and sent by the server and the client.

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up vote 0 down vote accepted

The built in windows firewall was preventing the machines from receiving the DHCP requests. Disabling this allowed them to join the network

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