Here's a way to make the DIR-615 C1 wireless work to get you on the internet. This isn't a solution for everybody because it works by bypassing some of the new features of this router.
I have a DIR-615 ver.C1. Followed all instructions and used automatic setups to get initialized. All 4 wired ports worked great but wireless could not connect, or couldn't renew IP address, or established a "weak" connection with no browser connect.
Next, I updated the firmware from 3.01 to 3.11NA. Finally got a laptop to connect, ran for about an hour, then, when I fired up a second laptop, I was stunned to see the 1st laptop lose signal and the 2nd pick it up. Then the 2nd laptop lost it's connection and from then on, neither would work together or alone. Any engineers or software developers that get a sniff of this suspect one thing: bad code in the firmware!
I've spent days on this product and am convinced that the firmware routines for auto channel scan or auto security mode are not fully tested or simply do not work reliably.
Here's what DOES work though! Force the router to work on a fixed channel and in a fixed security mode.
1. Choose Manual Wireless Setup
2. Disable Wi-Fi Protect
3. Disable Auto Channel Scan - set to CH. 7
4. Set security mode to WPA-Personal
5. Set WPA mode to WPA only
6. Set Cipher to TKIP
Note: no reserved IP addresses, no MAC address filtering or other fancy features employed