This is an ongoing issue that has been occurring ever since I first moved to DD-WRT and then to shibby Tomato.
I am using Windows 7 64 bit with a RT-N16 router (BCM4716 chip rev 1 pkg 10, 480 Mhz), getting internet through a Cisco DPC3008 DOCSIS 3.0 cable modem from Charter ISP.
I recently upgraded the firmware to run ddwrt.v24-19342_NEWD-2_K2.6_mega, then jumped to Shibby K26USB-1.28.9052RAF.
I am connecting to the RT-N16 through an NVIDIA nForce Networking Controller, one of two on my mainboard (the other is the same type).
After upgrading, I successfully booted and set up the wireless on the router and am able to see it on the wireless network. However, when I attach my cable modem's ethernet to the WAN port on the router, I will get internet briefly, then the internet connection drops and I am unable to access the router entirely.
The following method works on restoring the internet (briefly) and restoring access to the router (very finicky):
1. Power down the modem and router(s).
2. Disconnect the coax cable from the modem and wait 35 seconds.
3. Connect the coax and power up the modem.
4. Once the modem has a solid ready light power up the router(s).
5. Try to access the internet after 25 seconds.
As I said, this works, but it only lasts for a few minutes. If I try to connect wirelessly to the router, the router immediately drops off and I have to power off and do a hard reset to reach the router again.
I use 192.168.1.1 and have set my IP connection to statically use 192.168.1.5, with a subnet of 255.255.255.0 and a gateway of 192.168.1.1.
Even after doing this, I still cannot see the router through a browser or via ping (I will get time out, host unreachable, or general transmit failure).
Eventually, the only way to get the router to let me into the config menu is to do a hard reset (30/30/30).
However, just tonight, powering off the router and reconnecting/reseting/hard reseting it has proven unreliable. Currently I have both my PC and router off to try and alleviate the issue.
Update: I have left the PC off, connected nothing but the router and modem, and then attempted to wirelessly connect from my laptop. The laptop connected to the router for 30 seconds, then the connection dropped and I could no longer see the router.
I've tried the above along with setting the IP filtering to
Maximum Ports: 1024
(For an 8MB RAM model set it no higher than 1024)
TCP Timeout (s): 90
UDP Timeout (s): 90
I have tried empty wireless channels, DHCP vs. static settings on both the PC and router, cloning my PC's MAC to the router, using the other NIC on my PC, and thoroughly flashing the nvram. I have read countless forums and tried different methods.
Even after this, I still have issues with the router and the modem combination.
The cable modem works flawlessly when hooked up to the same mainboard NICs (when both are set to automatically gain an IP). I can get internet just fine this way, but obviously it renders the router an expensive and useless novelty if I can't have my peripherals on my internet.
I would appreciate any assistance. Please let me know if you need any further information.