Router is slower than 100Mbps

[Kelbi]

Hi!

My ISP changed my net speed to 120M/10M, 30M/5M guaranteed. I've used their speed-o-meter, and it showed only 28M/7M. I called them, and eventually we've figured out, that my router causes the problem. When I connected my notebook to the modem directly, I'm getting the max 120M/10M speed. So, I've upgraded my router's firmware, still no change.
My router is an Edimax BR 6104K, and it supposed to have a 100M connection on every LAN port and the WAN port. I would be more than satisfied with that 100M.
Anyone knows any solution? I would buy a new router, but I don't want that to be pointless...

Update:
LAN ports seem to be OK, so the problem is with the WAN port. But what's the problem?

[trogers]

Is your network adapter set to run on full duplex?

[YeOldeStonecat]

You need a router that has the "horsepower" to keep up with your internet connection. Many of the newer generation models will have a fast enough CPU and enough memory to sustain throughput above 100 megs. But the more entry level models, and especially older generation models, do not. Years ago most home grade routers were able to handle 8 - 10 meg connections....as newer generation models came out to keep up with the faster internet connections...this number goes up. Most models purchased in recent years will have 100 meg LAN and WAN ports..but it's the processor power of the router itself which determines throughput speed.

A quick search on Google shows a few articles showing that your Edimax BR 6104K model is capable of 40 megs of throughput.