Hey:
The DI-524 is a pretty good unit, I'm surprised it's slowed up. I have a DI-624, the so called super G. I run at 5-6 Mps on my wireless no problem at 100Ft.
A few points to note.
1) G speeds work only when G only broadcasts are sent, so if your using B cards anywhere or your laptop is internal B rather than G then know that your total speed possible is 11Mps not 54 Mps even if some cards on the net are G. (Your router firmware can force only G if you want.)
2) Distance does matter with antenna's it matters a lot!!! If your only starting with 11Mps you might be capping at the 1.2 because of signal loss. I know you said 1 foot, if you were above or before the unit by a couple of feet that really matters. I have Hawking omnidirectional high gains on my wiresless, it really helps. (about 25 bucks at new egg.) Try testing with the laptop and the router at the same level with antennas close and parallel if possible, then move away in increments to confirm if it signal loss over distance. PC mag article shows MOST units loss 50% of throughput at 1 FOOT and those are under controlled test conditions!!!! SO if your 11Mps at 50% you get the idea. It gets ugly fast best case!!
http://www.pcmag.com/article2/0,1759,1574323,00.asp(Sorry, I can't find the article that really explains the signal issues, I've lost it!!, I'll keep looking and if I find it all send.)
3) In your router check under the performance settings and insure it's set to Auto rather than some lower default.
4) Move the Antenna away from your desktop.
5) Also I haven't had issues, but folks do complain that microwaves, cell phones, house phones KILL wireless networks. Make sure your not testing with any more "noise" than you have to.
Lantom
Let me know what you find, I'm doing some looking on the DI-524 so I may post again.