The D-Link DWA-556 Xtreme N PCI Express desktop adapter is of little use when attached to a recommended D-Link wireless router and of less use anywhere else.
D-Link are a Canadian company who sell goods made in China. In Sydney, Australia, not the Sydney in Canada, D-Link products are cheaper than Netgear and more expensive than TP-Link and other Chinese made products. Most of the D-Link products I test appear to be ahead of the rest for new features but some of the new features fail to work. You might as well buy TP-Link to save money or buy Netgear for reliability. See similar comments about the D-Link DWA-160 Xtreme N dual band USB adapter.
The D-Link Xtreme N range advertises speeds up to 300 Mbps (300 megabits per second or about 30 megabytes per second) but achieved only 1 Mbps in a simple test.
The D-Link DWA-556 has three antenna so close together they do not have any real advantage over a standard antenna. The three antenna are so short they do not clear the metal case of the computer. The antennae are of no use around the back of your computer if they have to communicate with a wireless router facing the front of the computer. A better approach would be short cables to the top of the computer and three antennas spaced across the width to the top.
The D-Link DWA-556 is advertised as 802.11n speed then in the fine print it says (draft). Generally anything marked 802.11n (draft) was rushed out before 802.11n was finished and may have compatibility issues between brands. You might be able to use a D-Link 802.11n adapter with a Netgear 802.11n router but you are unlikely to succeed with a D-Link 802.11n (draft) adapter with a Netgear 802.11n router or a D-Link 802.11n adapter with a Netgear 802.11n (draft) router. A D-Link 802.11n (draft) adapter should work with a D-Link 802.11n (draft) router but in this case did not.
The D-Link DWA-556 reported low signal levels when in the same room as the The D-Link wireless router. I turned the computer to make the D-Link DWA-556 face towards the router for the clearest signal and still the signal was weak and intermittent. This D-Link 802.11n (draft) adapter must be using a different draft to the D-Link 802.11n (draft) router.
I threw the DWA-556 in the rubbish bin except for the cardboard box which could be placed in the paper recycling bin.
Room to room
When a router and two computers are near each other in the same room, you can connect by cable to get 1000 Mbps. Connecting to the next room is inconvenient because you trip over the cable going through the doorway. Wireless is better. I tested from one room to another through a wall containing no metal because metal can absorb radio waves. I tested in a building with no competing networks and no microwave ovens or anything else that might interfere. The router produces connection speeds from 34 Mbps up to 54 Mbps to Toshiba and other brands of computer.
Two hours of work did not connect the D-Link DWA-556 to the router. Just 20 minutes wasted on the D-Link made the D-Link dearer than the Netgear equivalent. Given the time I wasted on the D-Link device, I could have paid a network person to deliver an adapter, plug it in, and configure it for less than the money I lost on the D-Link. I could have paid a network technician to add a wired Ethernet outlet to the other room for less cost and I would have GigaBit access speed instead of MegaBit speed.
The test indoors failed so badly that I did not try building to building.
Wireless has a bunch of connection standards with 802.11n being the latest for high speed connections. 802.11n is still a long way behind a standard Gigabit wired connection. 802.11n is only useful when you want to walk outside or move from one room to another. The 802.11n standard was in draft form for many years. D-Link were one of the first companies to advertise 802.11n devices with
draft always buried in the fine print.
I pay good money for D-Link products and they blow up or fail in some other way. The 802.11n draft products behave badly.
A lot of companies have had problems with 802.11n draft products connecting to different brands but a brand X adapter usually connects to a router of the same brand.
The ultimate insult to the environment is to manufacture something so bad that people throw it without using it. The cardboard box and internal spacer are recyclable. The plastic bags or not. Some of D-Link's competitors are already labelling plastic packaging for recycling.
I have one network built on TP-Link and another on Netgear with both working better than the D-Link network. The D-Link based network had two out of three router/hubs fail in one year. None of my Netgear routers or hubs failed including ones from more than ten years ago. The TP-Link devices purchased about the same time as the last round of D-Link devices have not failed.
The Netgear devices all work straight out of the box. One TP-Link wireless router had a difficult Web interface until I downloaded a firmware update.
(Update 2010) The latest Netgear wireless routers have no external antennas. My TP-Link wireless router in this office has three external antennas. TP-Link also sell external high gain extended antennas for the same router at a very reasonable cost. I could not get the same arrangement off the shelf for either Netgear or D-Link. D-Link have some nice sounding external transmitter/antenna devices at many times the cost of the TP-Link equivalents with no discernible difference other than an occasional fire rating for USA. Given that I do not place outdoor transmitters indoors within air conditioning ducts, I am unlikely to pay hundreds of dollars extra for a special fire rating.
Do not bother with D-Link for
Xtreme performance with anything where the fine print says 802.11n draft. My DWA-556 went in the bin.