I'm having issues with routing traffic from wired devices to wireless devices on my home network using Comcast's Technicolor DPC3941T cable modem.
When I try to open a TCP connection from a wired device on the network to a wireless device on the network, the packets are never delivered to the wireless device. The wired device goes through a lengthy sequence of timeouts and packet re-sends, and eventually attempts targeted ARP requests directly to the wireless device, which also fail to get a response. Eventually, after around 15 seconds of messing around, the wired device gives up and sends a broadcast ARP request to the entire network. The wireless device responds properly and traffic can then move normally. After terminating the connection and waiting for around 5 minutes, the router "forgets" where the wireless device is again, requiring the entire timeout and ARP request sequence again to initiate a new connection.
Wired-to-wired connections work correctly, wireless-to-wireless connections work correctly, and wireless-to-wired connections work correctly. It is only wired-to-wireless connections that lose the ability to route traffic after 5 minutes. I've tried several different wired and wireless devices, and this only appears to happen when the wireless device is relatively "quiet" and doesn't regularly broadcast all sorts of junk onto the entire network. I've confirmed to the best of my ability what is going on with a packet sniffer.
To me, this smells like something screwy with the firmware on the cable modem.
Have you first tried powercycling / re-starting the device ? No joy ? Try hard resetting the device to factory defaults by pressing and holding in the recessed reset button on the rear for 30 seconds. This can sometimes clear up some weird behavior issues. You will lose any customized settings if you do the latter and they will need to be re-configured from scratch.
Thanks for the reply. I had power-cycled the router, but it didn't help. I had not done a hard-reset to factory default settings, so I went ahead and did that just now. No help there either. It still loses the ability to route from wired to wireless after 5 minutes of inactivity.
Thanks. Honestly, I'm not excited about having to do battle with the front-line support to convince them that there's actually a problem, and that I would need to exchange the router.
And, it's my belief that this isn't a hardware issue, so swapping it shouldn't fix anything. If it was doing something like hanging randomly or resetting randomly or failing to route all packets or corrupting data, I could believe that it's hardware. The fact that this is a very specific, perfectly repeatable, failure of a very small subset of its capabilities, and the fact that it always loses the routing info for the wireless devices after precisely 5 minutes of inactivity, this smells like a firmware issue to me. Somebody programmed that 5 minutes in there.
Are there any alternatives? I'd love to hear from someone who works on the firmware for these, or from someone in their orbit who can offer advice.
Hi there, djglaze. I want to help improve your experience. I work directly for the corporate office.
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Hi there, djglaze.
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