Don't think that DIR-615 is a lemon, at least not the hardware. In my experience, the firmware can present problems.
You don't say your hardware type, but I guess that it is C something. I believe that there is a firmware upgrade available to you, 3.12NA. (This assumes you are in North America. If not, try the D-Link website for your location.) I would try that first.
(ftp://ftp.dlink.com/Gateway/dir615_revC/Firmware/dir615_revC_fw_312NA.zip may be the correct link, or logon to the D-Link website and click through to the support resources for the DIR-615 router.)
If that doesn't help, consider trying DD-WRT firmware. (See www.dd-wrt.com.) Many think it is better than the stock D-Link firmware. However, be aware that using third-party firmware may void your warranty and you use it at your own risk. I am running DD-WRT firmware on a Linksys router and it works very well. Unfortunately, it is unavailable for my DIR-615 router, because I have hardware version B2.
The firmware in my DIR-615 router took a lot of tweaking before it worked correctly--a lot of trial and error and Google searching for ideas and suggestions. I actually wound up using firmware from the D-Link UK website. (So I have probably voided my warranty. It was a risk that I was willing to take.) The situation is complicated when you are trying to connect multiple devices that may have different networking hardware. I have a home network with up to four laptops, a desktop, two printers, and a repeater access point (DD-WRT firmware converts the Linksys router to a repeater access point) to get the signal to the front of the house. (The house isn't very big, it just has several closet doors with mirrors that weaken the signal.) It took me a long time to get everything working correctly.
I hope this helps. Good luck!
