Slower than advertised speeds

My current internet plan is supposed to give me 28Mbps download, and 1Mbps upload, but according to Speedtest.net, I only get around 12Mbps non-peak, although the upload remains constantly basically how it should be. My question is, why am I not getting the speeds I should? Is there something the ISP can do about this? I have a Motorola SB6120 cable modem (DOCSIS 3.0). Using Windows 7 on both of the computers I usually use. I have configured the routers for the optimal wireless signal quality, so that should not account for the majority of the speed deficit (especially since right now I am less than 10 feet away from the router). Any suggestions?

 

What type of wireless is your router using (802.11x)? It almost sounds like your running at near 802.11b (11 Mbps).

You mentioned your upload remains constant, but what about your download speeds? Do they remain constant as well or does it bounce around?

Have you tried performing the speedtest with a wired Ethernet cable?

 

Wireless limitations probably do account for the speeds you are seeing.
I do not recall if this issue is addressed in the article I will link you to, but also be aware that you can have an N router, and N wireless card and have your G speed Wii connected at the same time, and the entire router will switch to G speeds. Most home routers can't run two protocols at once so it "dumbs down" all of the connections.

Wireless explain by our very own Major! See the article http://majorgeeks.com/page.php?id=37

 

It's not the wireless because it does the same thing when I plug my laptop into the modem directly. The download speeds fluctuate a lot, but the upload remains relatively consistent. The wireless is broadcasting in mixed mode, but the wireless isn't the issue.