Local network shuts down stick modem inernet connection

[watcha]

Hi all!

I have successfully connected my two Windows7 machines via local network (Ethernet) - it worked automatically, no setup was needed. Everything is fine, for example I'm able to use a share mouse utility via the local network and control both computers with the same mouse. However once the network is swtiched on, my stick modem mobile 3G internet connection is shut down (the browser reports DNS name not resolved error). If I turn off the router the internet connection immediately returns. I tried to disable the firewall but to no avail.

Any idea as to how enable both the local network and the 3G internet connection at the same time?

thx

 

[watcha]

My related (though less important) problem is that if I try to share my internet connnection between the two machines, the local network collapses. When I disable the sharing the network immediately returns.