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  1. #1
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    Comcast Internet Howto

    A friend of mine has Comcast Internet, and is experiencing numerous "stalling" occurrences during her Internet sessions. Her XP Pro PC is hardwired to a Linksys BEFW11S4 router, which also feeds a laptop and a TiVo wirelessly. Router is connected to a SurfBoard modem. Her PC is fully patched, and I've run Ad-Aware and Spybot.

    I tried to trace the route of the incoming cable back to the entrance point on the house yesterday (having some problems because the entire basement has a drop ceiling). It appears the incoming cable runs to a Regal DS4DGH10 splitter. From there, a lead goes to a Regal GRS3DGH 110db EMI Isolator, and the lead to the cable modem takes off from there.

    She called Comcast this week, and the tech who showed up said he couldn't find anything wrong (he didn't look at anything in the basement, though). I have the receipt the tech left, and it has some numbers about signal levels, but I have no idea if they are good or bad. The TiVo, which is using a DLink USB wireless adapter, was showing Poor (24%) to Marginal (28%) connectivity most of the time I was there, with an occasional jump to Fair (58%).

    I downloaded a firmware upgrade for the Linksys router, and the download speed started out at 113 kbps, and gradually went up, never breaking 200 kbps. Applied the upgrade, but no change. Noticed the Internet light was flashing constantly on the router, which looks odd to me (my Linksys WRT54G, on a DSL line, has a constant Internet light).

    Any suggestions as to what might be wrong gratefully appreciated, or even a pointer to somewhere I can see what an "optimal" cable Internet wiring pattern should be (I seem to remember seeing that the incoming cable should use a special 2-way (Internet and TV) splitter first, then further splitters on the "TV" side as needed). I'd like to eliminate any cable miswiring before looking any further as to why Internet Explorer is stalling.

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    Re: Comcast Internet Howto

    Go to the following sites and do some real speed testing. Java will be required to be installed.
    http://www.dslreports.com/stest There are several different tests here, try at least 2 of them.
    http://www.numion.com/YourSpeed3/index.html

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    Re: Comcast Internet Howto

    Dave,

    >> Go to the following sites and do some real speed testing. Java will be required to be installed.
    http://www.dslreports.com/stest There are several different tests here, try at least 2 of them. <<

    I already tried the first site, the first time I went over to her house. Couldn't get the test to run to completion, before the connection stalled!

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    Re: Comcast Internet Howto

    Does the laptop have the same problem?

    If the laptop has a NIC connector, hook it up to a wired port and see if it has the same speed. If not then it is the computer.

    What NIC is in the desktop computer?

    Now running HP Pavilion a6528p, with Win7 64 Bit OS.

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    Re: Comcast Internet Howto

    Dave,

    >> Does the laptop have the same problem? If the laptop has a NIC connector, hook it up to a wired port and see if it has the same speed. If not then it is the computer. <<

    Don't know: the laptop belongs to her son, and he wasn't around on either visit. I'll try to go by sometime when he's home. Or I have one of those Compaq iPaq's (small desktop PC) that I could take over there, for testing.

    >> What NIC is in the desktop computer? <<

    I'll have to check.

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    Re: Comcast Internet Howto

    I would hazard a guess that this problem may be caused by (lack of) signal strength. Not being a technician, I may be entirely wrong on this however. But if I read your "wiring diagram" correctly, the cable modem is on one arm of a three way splitter, which in turn is plugged into one arm of a four way splitter. If I'm not mistaken, both of these splitters are passive devices (i.e. no signal boosting). Depending on what is plugged into the remaining arms of these devices, it may be entirely possible that the modem is simply not receiving an adequate signal.
    John
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    Re: Comcast Internet Howto

    DaveA,

    >> Does the laptop have the same problem? <<

    Finally went over to her house yesterday with a Compaq iPaq (small desktop PC). No stalling problem with it, so I hooked her PC back up and ran some speed tests. They showed much better speeds than the last time (2.1-2.4 Mbps), but still substantially below the 4 Mbps Comcast alleges she should have. I got into the cable modem and printed some stats from it: would anyone hear know how to interpret them, if I post them?

    >> What NIC is in the desktop computer? <<

    Realtek RTL8169/8110 Family Gigabit (onboard, it appears).

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    Re: Comcast Internet Howto

    Rebel,

    >> Depending on what is plugged into the remaining arms of these devices, it may be entirely possible that the modem is simply not receiving an adequate signal. <<

    I have some stats from her Motorola SB4200, but have no idea what they mean. Would you?

    Downstream
    Signal to Noise Ratio 36 dB
    Power Level -1 dBmV

    Upstream
    Power Level 56 dBmV

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    Re: Comcast Internet Howto

    I'm not a technician and I really can't say what these numbers should be. Perhaps someone knowledgeable in this area will jump in.
    John
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    Re: Comcast Internet Howto

    Rebel,

    >> I'm not a technician and I really can't say what these numbers should be. Perhaps someone knowledgeable in this area will jump in. <<

    Somewhere else I found info on what the signal strength numbers should be. Yesterday I bought a "low-loss" 1-to-2 splitter and rearranged things, so that the cable modem was fed off one its legs, and it was the first splitter on the incoming line. Fed 5 televisions off the other leg. The Upstream Power Level on the cable modem went to 52 dBmV immediately (it should be lower than 55) and the Upstream Power Level went from -1 dBmV to 3. Ran a speed test at the Speakeasy site after that, and Download Speed jumped to 5464 kbps. So I think I licked this problem <grin>. Have to wait until she runs a couple Yahoo! Games sessions to be sure, but things are looking good right now.

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    Re: Comcast Internet Howto

    Well it certainly appears that signal strength (lack of) was the problem. I'm surprised that the Comcast tech didn't pick up on this. Thanks for posting back.
    John
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    Re: Comcast Internet Howto

    John,

    >> Well it certainly appears that signal strength (lack of) was the problem. <<

    Don't I wish [img]/forums/images/smilies/sad.gif[/img] My friend just called and said she's still having the "stalling" problem. I asked her to dump the router and run the PC directly off the cable modem for a couple days, to see if that helps. If that doesn't, about all I can think of would be 1) try a different NIC, or 2) do a Repair install of XP Pro.

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    Re: Comcast Internet Howto

    When you did your signal strength test, were all of the other devices (TV's & whatever) on or off? Does this problem manifest itself with the other devices on, off, or either way? Let us know what happens with the direct cable modem setup.
    John
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    Re: Comcast Internet Howto

    John,

    >> When you did your signal strength test, were all of the other devices (TV's & whatever) on or off? <<

    I ran the test first with only the cable modem connected to the 1-to-2 splitter, then connected the TV runs. The signal strength numbers didn't change between the two tests.

    >> Does this problem manifest itself with the other devices on, off, or either way? <<

    2 of the TV's are in her boys' bedrooms. I doubt I could keep both their TV's off long enough to see if the PC problem goes away <grin>.

    >> Let us know what happens with the direct cable modem setup. <<

    Will do.

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    Re: Comcast Internet Howto

    I would think that with the TV's on, they would be drawing signal (and probably degrading the signal to the modem), but as I indicated before, I'm not a technician so I can't give you a definitive answer on this. Might be worth running another few signal strength tests, one with the other equipment on and another with the other equipment off.
    John
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