Have you tried updating the firmware? Go to d-link's website and download the newest firmware and try to update it.. sometimes that can help (remember to follow the instructions and use a computer that is connected via ethernet not wireless to update it)
D-Link Wireless N Router
Also check your cable that goes from your cable / dsl modem into the router, it looks like it keeps disconnecting...
You can also try hitting the DIR-615 with a hammer, just hit it a couple times with a hammer and then throw it in the garbage.