Cannot obtain IP address from routers when switching between networks.

Thanks, I'll try it.

I had that problem when I came from work to my home wireless system. The problem was that (somehow), the computer (or wireless device) retained the gateway of the other network. That is, in trying to obtain a DHCP address, the system would try to contact 10.18.8?.? instead of 192.168.?.? . Of course, the system should broadcast to obtain a new IP address. I don't know if it is a problem with the device or with Windows (though I suspect it is a Windows bug).

Anyway, solved the problem by using devcon.exe (Microsofts command line device manager) to restart the connection. Used a logon script to restart the device.

Devcon.exe can be obtained here:http://support.microsoft.com/default.aspx?scid=kb;en-us;311272

Perhaps you could try just releasing and then renewing your IP address lease. Since address leases can be obtained with a long duration, your computer may be trying to hang on to that lease.

To manually do this (without the GUI), launch a command window, then type

ipconfig /release

to chuck your old IP address away. The computer should respond with a new IP address of 0.0.0.0. Then type

ipconfig /renew

to force the system to request a new IP address. If successful, you should see a new IP address onscreen; otherwise, it will respond with an error message that will give you some clue as to what is happening (e.g. Unable to contact DHCP server).

&^)

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@adamer wrote:
Perhaps you could try just releasing and then renewing your IP address lease. Since address leases can be obtained with a long duration, your computer may be trying to hang on to that lease.

To manually do this (without the GUI), launch a command window, then type

ipconfig /release

to chuck your old IP address away. The computer should respond with a new IP address of 0.0.0.0. Then type

ipconfig /renew

to force the system to request a new IP address. If successful, you should see a new IP address onscreen; otherwise, it will respond with an error message that will give you some clue as to what is happening (e.g. Unable to contact DHCP server).

&^)

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That should work, but in the instance I mentioned where the system is retaining the address of the gateway which no longer exists, it doesn't work. The wireless device just fails to obtain a DHCP address. That should never happen. The device should broadcast for a DHCP server. That it doesn't is either a problem with the device drivers or with the OS -- and I don't know which.

Jerry,

This suggestion is likely too obvious - make sure you don't have a default gateway statically set in the TCP/IP properties for the connection. Another possibility is that there's a problem with the Winsock 2 "Layered Service Provider" chain. Those can usually be fixed with WinsockXPFix or lspfix.

Jim

OK Fixed LSP entries. Will see if it makes a difference (turned off devcon logon script too).

Looks like LSP may have been the problem. Connected at home after work today with no problem. I don't pretend to know anything about LSP, so I can't know.

Jerry,

If you're interested in learning more about "layered service providers", here's a diagram from a provider of a LSP product showing how it affects the way the system handles TCP/IP traffic, and a Microsoft technical article describing the feature in depth.

An example of a beneficial layered service provider is software that scans incoming EMAIL for viruses. Since all (non-Web based) EMAIL uses the "simple mail transfer protocol" (SMTP), a Layered Service Provider can examine all SMTP traffic for the presence of viruses.

A hostile LSP may divert certain types of traffic, like traffic bound for Web sites, to a hostile Web site. The fact that fixing the LSP chain (more than one LSP can be present, good and bad) fixed the problem suggests that it would be a good idea to check for the presence of malware using Ad-Aware and Spybot.