I own a DCS-5020L and DCS-5010L, neither of which experienced any range/connectivity issue. As chuckers points out, I would look at the IP address (static?) and make sure the DCS-5010L IP range is within the same range defined by your router.
I recommend leaving all cameras and router on DHCP, and reserving IP addresses for each network camera in the router. Stay away from static IP addresses as these can cause a conflict and possible connectivity issues unless carefully maintained.