Problem with router and USB dock

[CarvedDuck]

Using Buffalo router and DD-Wrt connected to the laptop and I can see the other PCs on the wired network. I have my phone Tethered for Internet direct to laptop. With a browser I can access the Internet OK and login to the DD-Wrt on the router.

I just got a USB-3 dock which has a network port. If I take the Cat5 from the laptop and plug it into that dock-port, I can see the other PCs OK.

But, when I load a browser to access the Internet it hangs and times out. Chrome returned an error saying "Could not resolve DNS server."

I am running the router in the default set up and all PCs have static IPs.

Are there some settings I should be using with the router that might help this situation?

I think the dock is assuming my Internet is coming via the router and it sends out a request for the DNS. Meanwhile the laptop (win8) is doing the same through the wifi and one or more of the laptop, win8, the router or the dock are getting confused.

I'd really appreciate some help with this as the dock will save me plugging in/out 5-connections every time I walk away from the desk with the laptop.

Thank you.