I too installed SharePort 3.1 and it still didn't see anything plugged into the USB port on the router and my custom built desktop. It got me to wondering. What is the difference between my wirelessly connected laptop, which works with SharePort 3, and my hardwired desktop(besides Vista 64 on laptop, and Win. 7 64 on desktop). It is the connection. I wondered if there was a driver issue between my Marvell Yukon 88E8056 PCI-E Gigabit Ethernet Controller on my ASUS P6X58D Premium Mobo Desktop and the DIR-825 Router.
Well, I was correct. I uninstalled the Ethernet drivers(2 ports), the driver that has worked fine for Internet through the router this whole time, and I installed the original driver from May 2009. The DIR-825 and the printer showed up immediately in the SharePort Utility 3.1. I went ahead then and went to Marvell's website and downloaded the latest driver from them, which is from Feb. 2011, and updated the driver to it and it still works fine.
The last time I updated the Marvell driver, it came through Windows Update. I don't know if there was a compatibility issue with the DIR-825 or if the driver may have been in some way corrupted during install. Like I said, Internet connectivity worked fine.
I hope this information helps the many others having the same problem. There may be some issues with D-Link and\or Microsoft as far as driver issues on their machines and their routers.