# Solved: Comcast Internet Constantly Disconnects



## avisitor (Jul 13, 2008)

I'm constantly getting disconnected on my Comcast Internet. (It's my primary connection, but I do have a VZW BroadbandAccess as a secondary and for when I commute/go on the road, etc.) This has always happened, but mostly stopped after I switched to a 5-2200mhz 4-Way splitter about 6 months ago. Before that, the disconnects would be like every ten days. Now, it's happening every few hours. Sometimes it resolves itself, sometimes I have to disconnect and reconnect the modem from the cable line (powercycling doesn't do it). My cable modem is a real pain to get to, being at the bottom of a rack in my crawlspace. It's on a cheap 650VA UPS with the router and some switches.

It always fails on establishing send channels. Can tell that from the logs. (Which I can't seem to access anymore, but that's what it always used to be).

Modem: SB5100
ISP: Comcast, Chicago.
Router: WRT54G v. 6 on DD-WRT, but it doesn't really matter. Does the same thing when connected to my RouterBoard but that's not setup the way I want it yet .
Other Stuff: Airport Express as AP/Print Server/Speakers with DHCP turned off.

Should I just order a new modem? Any recommendations? Would a bidir cable amplifier before the splitter help?


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## TerryNet (Mar 23, 2005)

> It always fails on establishing send channels.


When that exact thing happens to me it's almost always a coax connection. A couple times it was the connection of the modem cable to the wall jack--rubbing off a little invisible oxidation with a pencil eraser and reconnecting was the fix. Three or four times (I'm an slow learner  ) it was a visibly rusted connection outside where the cable company's line meets my cable and the ground connection. (Petroleum jelly, electrical tape and duct tape have that pretty well under control now.)

In short, check all the coax connections beginning at the modem.

Occasionally the problem was ISP, but usually an ISP problem is indicated (on my system) with failure to get a solid Receive signal.


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## avisitor (Jul 13, 2008)

All right, next time it goes out (which will probably be in a few minutes), I'll go take an eraser and clean all the connectors. (Should I just put new F connectors on? I have a bunch...)

I'll change the grounding block outside tomorrow. Gotta get a new one.


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## TerryNet (Mar 23, 2005)

If it were daylight I'd say start with the outside.  Doubt that you need new F connectors, unless one looks really bad.


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## avisitor (Jul 13, 2008)

I'll check outside tomorrow. I could do it with a flashlight, but... It's not that it isn't bright enough in the city at night. Way too much light pollution . You're lucky to be far enough away from it all so that you can actually see some stars, not just whatever airplane happens to be landing at O'Hare .


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## JohnWill (Oct 19, 2002)

If it's a Comcast modem, I'd have them fix it.


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## avisitor (Jul 13, 2008)

I've called Comcast so many times it's not funny. I changed the grounding block and haven't had any disconnections since. Must have been corroded or otherwise interfering with the connection.

So, I think it's solved, but not absolutely sure...


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## JohnWill (Oct 19, 2002)

That's good.


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