Limited internet coectivity when coected to WiFi and USB-HSPA/3G

My setup is as follows:

1. An old Billion 400G router, not coected to the inteet
2. A new D-Link USB-HSPA/3G inteet stick

I need to coect to the router via WiFi to be able to print (I have a Canon 217w coected to the router via WiFi), as well as the inteet stick for inteet coectivity.

However, when both are coected, Windows indicates that there is limited coectivity on both coections - in other words, it doesn't pick up inteet from the stick when the laptop is also coected to WiFi.

Not very clued up when it comes to networking, but I do know that DHCP is enabled. I have tried bridging the coections, but that results in a very slow inteet coection from the stick.

So my question is this: how do I maintain both coections, and retain a high-speed inteet coection?