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Mystery internet connectivity issues

January 10, 2014 9:19:57 PM

I'm having fairly serious internet connectivity issues recently and unless the problem is with the cable line coming into my apartment or something else with my ISP, I am at a complete loss.

I've got Comcast cable internet, and I'm using my own SB6141 modem. I was using an older Surfboard modem previously (I forget the exact model number) and replaced it when I started having issues with it losing connection and restarting randomly. With the new modem I run with 4 bonded channels downstream and don't seem to be having the same issue anymore.

However, I will randomly get what seems like serious packet loss to the point where I can't even load webpages. Generally, if I restart my modem it seems to resolve the problem, at least for a while.

When I have the connection issues now, my modem, router, and computer all insist that I am connected to the internet, but I have to constantly refresh/reload a webpage to get it to actually load. I've gotten a speed test to work during this once, and it showed a nice ping (~50 ms) with less than 4 Mbps downstream speed and it timed out on the upstream test. Normally, when my connection seems stable, I run about 30 Mbps down and 5 up. I've also run some ping tests when the connection issues crop up, and I've seen anything from 15-20% packet loss pinging various web servers (mostly yahoo and google). The packets that aren't dropped still have decent pings, ranging from the 30 ms to 75 ms range.

I've cut my old Netgear N150 router out of the loop and run cat5 from directly from my modem to my computer, and it seemed to help for a while but the connection still became unstable after a while. I got a new Netgear N300 router today, and the issues are still happening so I think I can rule out the old wireless router causing the issues. My cable modem's signal stats seem solid as well, with 39 dB SNR and 1-3 dBmV power level on all downstream channels and 42 dBmV power level on the upstream channel. Signal stats also show uncorrectable codewords of less than 0.000004% (about 550 out of 91.5 million total codewords).

I'm just not sure what I should do at this point. I've had a few techs come out before I replaced my old modem with the new SB6141. One removed a splitter from box that someone was stealing cable with, and the other didn't do anything except tell me my signal levels looked good. I'm open to suggestions.
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