IP problem with WRT54G router

We have a very simple setup: Comcast Surfboard (RCA) cable modem to WRT54G router. 2 laptops with wireless cards (one 802.11b, the other


Problem: when my husband either shuts down his laptop (with the

802.11g card) or disconnects his VPN tunnel without shutting down his laptop, my laptop loses its connection. Rebooting my PC doesn't help. What cures the problem (every time) is to reboot the cable modem, then plug the router back in. It appears that something goes wrong with IP addressing.

From a look at the Linksys firmware download information, it doesn't appear this is a known/resolved problem. Could I have a problem with settings? Is this something I can work around? Do I have to buy an

802.11g card for my laptop to fix this?

Thanks for any pointers! Melissa

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does it happen when he is not using the vpn, jsut normal web surfing?

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Could you be more specific on what "loses its connection" means? Does it mean:

  1. Loses RF signal strength?
  2. Disconnects the radio (no SSID)?
  3. No route to the router? (Can't ping router)
  4. No route to the internet? (Can't surf)
  5. No DNS? (can surf by IP address, but not by name)

Weird. Assuming the WRT54G has not gone insane, the only way I could induce a 2nd laptop to go comatose when the 1st laptop is disconnected is if something in the 2nd laptop is going *THROUGH* the 1st laptop. Possibilities are:

  1. 2nd laptop connection to the internet is going through the VPN to a corporate connection at some remote connection.
  2. 2nd laptop is setup to use ICS (Internet Connection Sharing) or some type of Proxy Server running on the 1st laptop.
  3. Is there any VPN client software (PPTP or IPSec) running on the
2nd laptop? If, yes, turn it off and try again.

Do any of the above sound familiar?

The fact that it works at all means that it's probably in the settings and not in any hardware issues. No need to buy anything.

However, figuring out exactly what's misconfigured is gonna be rough. Can you supply some information here?

  1. Turn off the 1st laptop, reboot or power cycle everything, and see if the 2nd laptop works by itself (1st laptop off). If it works, then it's probably properly configured correctly. If not, then it's time to untangle the network settings. I won't offer any suggestions until the culprit is better identified.
  2. In the above arrangement (laptop #1 off), run: Start -> Run -> cmd IPCONFIG Record the IP address and the Gateway address. The gateway address should be the address of the WRT54G. If not, you have something radically misconfigured on laptop #2.
  3. Now, turn on the 1st laptop and run it as you would normally. Reboot laptop #2 *AFTER* laptop #1 has done the VPN thing and connected normally. Is the IP address and gateway the same as in test #2? If not, then laptop #2 is either getting its DHCP assigned IP address from an alien spaceship, through the VPN from some corporate server, or from laptop #1. Getting it through the VPN will show up as having TWO IP addresses, one of which comes from the router, the other from the VPN. If so, contact the corporate LAN admin and ask for info how how to temporarily disarm the VPN on laptop #2.
  4. My guess(tm) is that you have VPN software configured on both machines to use identical logins and authentication. When connected, your actual packets are not going through the Comcast CMTS gateway, but going through the VPN through the corporate server pretzel. When either laptop intentionally disconnects or logs out of the corporate VPN, both connections through the VPN drop resulting in no access. Laptop #2 apparently isn't smart enough to switch the default route from the corporate VPN gateway, back to the WRT54G.

That should be enough for now...

Reply to
Jeff Liebermann

I have read a lot of posts about troubles with the combination Linksys + VPN passthrough See e.g.

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More recent firmware versions do promise improvements though...

Reply to
Jeroen van Bemmel

In particular,

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mentions that 'Firmware 2.04.3' "Resolves issue with PPTP passthrough". Which firmware version are you running?

Reply to
Jeroen van Bemmel

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