Comcast Internet Howto

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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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Go to the following sites and do some real speed testing. Java will be required to be installed.
http://www.dslreports.com/stest%5B/url%5D There are several different tests here, try at least 2 of them.
http://www.numion.com/YourSpeed3/index.html%5B/url%5D

DaveA I am so far behind, I think I am First
Genealogy....confusing the dead and annoying the living

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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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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?

DaveA I am so far behind, I think I am First
Genealogy....confusing the dead and annoying the living

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

I'll have to check.

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DaveA,

>> Does the laptop have the same problem? <> What NIC is in the desktop computer? <<

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

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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.

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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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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.

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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 . 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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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.

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John,

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

Don't I wish 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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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.

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John,

>> 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? <<

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 .

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

Will do.

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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.

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John,

>> 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. <<

It appears they only have 2 of the 5 TV's on simultaneously, and I was getting the same modem signal strength with 2 running as I did with none turned on (not even connected to the cable, as a matter of fact).

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John,

>> 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. <<

My friend called again Tuesday morning to say the stalling problem was as bad as ever. When I asked if she'd tried plugging the PC directly into the cable modem, she admitted she hadn't. I had some free time, so I drove over to her house.

Before dumping the router, I checked the signal strength on the cable modem: still good. I had seen advice about using Belarc Advisor in a thread in the XP board, so I decided to run it before I did anything else. Belarc identified the motherboard as an MSI. My main PC has an MSI mobo, and I'm familiar with their Live Update utility. Installed that and ran a scan, and it advised me to download new NIC drivers. Did that, ran the scan again, and it advised me to download a much smaller file for the NIC (bug fix or the like, I would assume). After that, download speed was around 4400 kbps–not as good as the 5400 I'd seen a few days before, but not awful.

I told her to try the PC out for a couple days and see what happened. She called Friday to tell me she hadn't had any problems since Tuesday! So it appears the NIC driver was the major problem.

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Wow. I would not have thought that a driver would have that sort of fluctuating impact. Thanks for posting back and .

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