cable modem disconnecting w/uTorrent

[huge]

A couple of weeks ago I realized that I did not have static IP set up correctly. uTorrent was still working (not sure how) but I wasn't getting good speeds and the little network icon was the yellow triangle instead of the green "OK" mark it is now. When I fixed my static IP and made sure the port forwarding was correct, my speeds went way up (often well over 500kB/s down) and the network indicator is always the green check mark. OK, so far so good.

But lately (not sure it happened at exactly the same time I made the fix, but close) when I leave uTorrent running unattended, my (Comcast) cable modem (Motorola Surfboard SB5100) disconnects. It still has the right green lights (4 solid, one blinking) on the front, but I have no connection to the internet. I can always fix the problem by logging on to the modem through my browser and resetting it, after which uTorrent and everything else connects just fine again.

Oddly, in 2 out of the first 5 or so times I got disconnected, it was my router (Netgear WGR614v5) that needed restarting, but since then it has always been the cable modem and the router seems to be behaving fine.

I've tried lowering my bandwidth settings a few times but it still happens. I've only been messing with "Maximum Upload Rate" (currently at 70kB/s) and "Global max number of connections" (currently 50). Both of those numbers are well below the recommended settings for my UL/DL speeds. I haven't changed the Max Download Rate (set to 0 or unlimited), but I don't think that's the problem because it has frequently disconnected when I'm not downloading at all but only seeding.

I have DHT and Local Peer Discovery and Peer Exchange enabled. Should I play with turning any of those off?

net.max_halfopen is set to 8 ... I haven't tried lowering that number.

Are there other settings I should be playing with? I've tried various things suggested in speed troubleshooting guides, but the UL rate and max connections are the only things I've been consistently decreasing to see if that would bring about a fix.

Windows XP Pro, all service packs and updates etc.

Motorola Cable Modem (a few years old)

Linksys RT31P2 VoIP router (for vonage - I think this has NAT firewall)

Netgear WGR614v5 Wireless Router (with NAT firewall also)

Windows Firewall

Is this likely a hardware (modem) problem? Comcast getting pissy with me once my uTorrent speeds went way up? Any advice on what to try next?

Thanks for any suggestions...

[Switeck]

Disable:

UPnP, NAT-PMP, DHT, Local Peer Discovery, and Resolve IPs

Hopefully, you'll at least see fewer disconnects that way.

How is your computer networked to the cable modem?

Does it have to pass through both the regular router and the vonage router to get to the modem?

[huge]

Switeck - thanks for the super-fast reply!

I'll try changing those settings. Am I right that disabling at least some of those settings will likely result in slower download speeds? Should I try disabling one at a time to isolate what is causing me the problem or are they all just bad news and I should have them disabled anyway?

My setup is:

Comcast HSI Cable

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Motorola Surfboard Modem

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Linksys RT31P2 VoIP router

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Netgear WGR614v5 Wireless Router

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4 Desktops (only one running uTorrent)

That is the configuration that Vonage recommended 4 years ago - I haven't ever looked into whether there might be a better way to set things up, or tried to figure out if any of my old equipment might be causing a nasty bottleneck. Until Comcast's most recent speed increase it always seemed like I was getting bandwidth close to what they were advertising - now it's not so close, but still seems plenty fast. I keep meaning to plug a computer straight into the cable modem and checking to see if I get much better speeds - maybe I'll do that right now...

[Switeck]

You're double-NATed by the combination of the 2 routers.

Port forwarding that can be...tricky...at best.

If you leave all the hardware in that wiring arrangement, the Linksys RT31P2 VoIP router has to be forwarded to the Netgear WGR614v5 Wireless Router ...which then has to be forwarded to your computer.

[huge]

I think I had the forwarding set up correctly, and was getting good speeds in uTorrent, but are you suggesting that the double-forwarding may have thrown some added complexity at the cable modem?

Anyway, I've switched up the order of the routers, and more ... I'll put it in a separate post...

thanks for helping me out with this.

oops I guess I can't post twice in a row ... here's what I meant to throw into the next post:

OK, wow ...

I went off on a tangent to my original problem, and swapped out my old Netgear router for a TrendNet Wireless-N router that's been gathering dust on my shelf since Black Friday, and while I was at it I switched the positions of the new router and the old VoIP router, so things now look like:

Comcast HSI Cable

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Motorola Surfboard Modem --- Linksys VoIP router & phones

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TrendNet TEW-652BRP WirelessN Router

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4 wired Desktops (only one running uTorrent)

Before even playing with uTorrent I notice a phenomenal speed increase:

which is something like double what I was seeing before in DL speed.

I did have the Modem disconnect once in the middle of all my swapping cables around and running speedTest, but I'm hoping that was a fluke.

For now I'm going to sit on this for a couple of days before I introduce uTorrent to the mix. If the connection stays happy and then starts disconnecting again when I start uTorrenting, that should be a decent clue...

[Switeck]

Yes, the double router increases complexity immensely. Unless the "inner" one (farthest from the modem) is set up in bridge mode to act as a dumb switch, there's 2 separate LAN networks that are generally connected only 1 way -- outgoing from the computers.