thinkpad t420 - undocking internet stops have to release ip

[ewalker3]

I have a t420 attached to a docking station.
When i first got the laptop and dock i had no issue when i would undock the laptop the internet would continue to work without issue. At some point though it changed, whenever i undock the computer i have to do ipconfig /release then /renew to get the internet working, the wifi connection is active at all times, shows that there is an ip address etc.

i finally have a chance to look for some help on this. does any one have suggestions on how to fix this as its annoying?