I had the same problem as the OP, camera would still send pics for when it sensed motion, green light was on, but it would not stream live - on my Chrome, Firefox, Safari or iPhone app, inside or outside the same wireless network, and I could not wirelessly access the camera settings. When I disconnected and reconnected the power supply, the problem would be solved for another 5 minutes. This problem existed both before and after I updated the firmware.
In my case, I cannot imagine the issue was distance from the router, as the camera and router were fewer than 5 feet apart, with no obstructions.
I suppose I could try all the work around measures mentioned in this thread, but I bought the D-Link product because it was user friendly. When the ease of use disappeared, so did the value of the product.
Camera on its way back to Amazon.