Wow, that's the same problem I am facing with my DIR-615, HW:B2, FW:2.25 but now there are days when it dies 3-4 times in an evening for all computers on the network. When I try to browse to 192.168.0.1 I cannot connect to the router. A power cycle on the router fixes it.
As to FurryNutz standard questions, I am working with:
DSL
Standard modem, model Siemens Speedstream 4200,
DNS Addresses: Primary and Secondary both 0.0.0.0
Enable QoS Engine is deselected
Do not have Advanced DNS Services
Enable DNS Relay is selected
All devices have DHCP Reservations
Devices are set to auto-obtain
Firewall filtering is endpoint independent for TCP and UDP
Mode: mixed B, G, N
Other Modes: tried just G, tried just N
WPA-Personal, WPA2 Only TPIK and AES (there is not a WPA2/Auto option)
Wireless devices are several laptops, an apple tablet, a blackberry, an iPhone
The problem has occurred when there are no other networks visible and also when other networks are visible.
We have no cordless phones
Anti-virus and firewall have been disabled but in any case the problem happens on all devices, not just on mine
The point about turning off all devices while testing seems inappropriate. The failure happens occasionally and randomly. I cannot force a replication of it so there is no testing being done per se.
I do have a hardwired connection to my computer.