Saturday 18 July 2015

Cisco AnyConnect VPN reconnect resulted in different configurations settings error

This error is nothing to do with the Cisco setup or the configuration, well kind of. Its actually down to the packet size of the data on the network. You need to reduce the size of your MTU (Maximum Transmission Unit).

Quickest way is to start a Windows Command Prompt from Start > Programs > Accessories (in Win 7). Make sure you right-click and use Run As Admin.

Then type
   netsh interface ipv4 set subinterface "Local Area Connection" mtu=1300 store=persistent

or use "Wireless Connection" if appropriate.

You can also type
   netsh interface ipv4 show subinterfaces

to get a list of interfaces.

Or download a utility to do the job for you, c/o Cisco

Could be worth experimenting a bit to find what is the most appropriater MTU, using a higher value of 1400 might give slightly better performance.

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