in terms of d link router, you need to put a switch in between.
the same goes for cisco, zyxel etc.
I've had the same problem with the following servers / nas,
seagate black armor, Thecus 7700pro, ubuntu server.
Fix the problem by putting a dlinkswitch in between (connect all computers / servers to the switch and have only one cable from the router to the switch and your problem should be solved.
would like to point out that this little nugget is the first router that can handle my network without causing lag or die. (Over 50 clients that streams and plays, samba, wingftp, subsonic, plex, etc.)
can also mention the various routers I used before I found this. zyxel nbg5715, netgear wndr4500, Cisco E4200, jensen 89300th
/ Chali