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Channel 2012

Lost access to local network after using VPN program

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This is a weird one for sure. Last month, I was testing a VPN program (Cisco QuickConnect) for a customer to make sure that their setup works. Ultimately, the test was semi-successful, and we ended up pointing them in a different direction for VPN, but I lost access to all network resources on my laptop's Ethernet interface after that experiment. Here are the specifics of the symptoms:

  • Cannot ping the default gateway at my home office (192.168.1.1) any longer
  • Can ping an address on the Internet
  • Cannot resolve domain names
  • The wireless interface on the same is not affected, and is my only way to be able to use this network from this computer now
  • As the problem started to occur, some applications were still able to get out to the Internet, (assuming that they still had an active session of some kind going on) but others were not
  • No websites can be reached by name or by IP address

I uninstalled QuickConnect right away after this incident and tried again. No change. Tried clearing the Windows routing table. No change. Did a system restore to the time right before the offending program was installed (it was at least nice enough to create a restore point prior to installation). Still no change. Tried reinstalling the Ethernet driver as well. This also was ineffective.

To make a bizarre problem even stranger, this only happens on networks with the same subnet (192.168.1.0/24) that I was trying to connect to and from when the problem first occurred. Others are 100% fine and I can work all day long with the same Ethernet card on any other subnet.

I checked to make sure that no static IP addressing, DNS, or anything strange like that had been set by the VPN program. None had. Any ideas?

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You need to configure a split tunnel.

Uncheck "Forward requests to remote default gateway" to use a split tunnel.

I always use a split tunnel so that way I can continue accessing local network resources.

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Just to provide an update on this, I found that the problem, curiously enough, goes away if I configure a static IP address on that interface. After setting it back to DHCP, the problem immediately returns.

 

2 hours ago, Dylan Cruz said:

You need to configure a split tunnel.

Uncheck "Forward requests to remote default gateway" to use a split tunnel.

I always use a split tunnel so that way I can continue accessing local network resources.

I don't want a split tunnel, however. I do not have a VPN connected right now, nor do I plan to for the foreseeable future.

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What differences (if any) are there in IPCONFIG /ALL run with DHCP on and with static address?

Run with the DHCP on, run IPCONFIG /ALL>C:\dhcp_ipconfig.txt.

Set the static IP, net mask  and gateway the same manually and run again IPCONFIG /ALL>C:\static_ipconfig.txt.

Does the behaviour remains the same?

I.e. is the behaviour independent from a same IP address assigned to the machine?

The behaviour you decribe seems like connected to the gateway, so Dylan Cruz may be right, but he doesn't specify where to uncheck that setting (that BTW I doubt is called exactly as he stated).

Could it be the case of some port forwarding?

i.e. what do you get if you run:

netsh interface portproxy show all

? :unsure:

Anyway, unless you have particular settings, a:

netsh interface portproxy reset

should do no harm.

jaclaz

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