OT: Should I replace my cable modem?

[eric©]

I know, info on this is all over the net...but thought I might solicit the opinions of people I know and trust :P  This will be a bit long, I'm trying to be complete in the details :) 

I currently have a nearly 6 year old Motorola Surfboard 5101 modem for the cable internet.  We've been having nearly daily problems with this thing dropping off line for anywhere from 5 minutes to hours at a time.  The usual power cycling (both in software, and pulling the power plug), and resetting factory defaults within the software sometimes worked, mostly didn't.  

For a while I had it connected through a 2 way splitter with HDTV also connected, and found that the signal levels were borderline to the modem.  I pulled the splitter, connected directly to the wall socket, and signals got quite a bit better, dropped offline less, but still well beyond annoyingly frequent.  

Checking the logs showed that it was always failing at getting an upstream ranging response - T3 timeout.  This was also the case today when I called Cox.  

I also have a Cisco DPQ3212 modem sitting here left over from when we got Cox phone service installed last year for a few months time (needed to have a "land line" for some equipment for a short time), that has since been cancelled.  Apparently the modem was supposed to have been returned to the Cox store, and never did, and Cox never noticed..oops :P  

I called Cox and had them check the Motorola - they said they can't even see the modem on the line.  We switched the Motorola out for the Cisco, and it came right to life, and internet working for now...yay!  Problem is that this is supposed to be a leased modem, and will be costing us $10/month to run.  So I figure if I have to replace the modem, I'll be buying something from Fry's/Amazon/Newegg/whereever rather than leasing this one. 

I told them to go ahead and leave it going for a few days to make sure the modem was the problem, and not the lines/signal level/something else.  If this stays up and going without dropping out, then that will be my cue to go ahead and buy another modem.  

All this said, does this sound right?  Do cable modems fail in this manner?  Or is there perhaps a signal/noise issue on the line that I should Cox investigate that's just being masked by a newer/potentially more sensitive modem?  I don't mind having to buy a new modem if that's the case (it DOES seem like this Cisco is a bit more zippy than the Motorola ever was, despite we having a 25Mb down, and DOCSIS 2.0 is supposed to be good to 30Mb down), and HD youtube streams are no longer buffering halfway through, I just don't want to be spending money I don't have to if this is actually a Cox issue.  

thanks

Eric

[John Sugg]

Eric,

My first guess is you have an intermittent signal issue. Visit all your RF connectors with your 7/16 wrench. You might be surprised that 1/2 turn loose will create signal problems. If you have an aerial drop you probably won't be able to check the connector at the pole. If you have an aerial drop go to the cable above the bonding location and bend the coax a bit with your hand. If it makes a crunchy sound, your drop needs replacement. Squirrels love to chew drops that are in their path on the cable strand (aka squirrel highway). Water enters the chew hole and the coax shielding starts to corrode. Crunchy coax = corroded coax.

Modems must be connected to the first splitter or your return loss will be too high. It sounds like you have that set up right. The Moto 5101 always seemed very reliable so I doubt that it is the problem.

Ranging is when the modem is communicating with cable headend equipment to properly set its return output power level. A signal issue can create the T3 timeout error code you are seeing.

If you can't resolve by checking your coax and fittings, you might need the dreaded service call. 

John

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[eric©]

I would guess it's underground service, considering I have a cable termination box of sorts at the end of the driveway...and come to think of it, it did once get hit with a monster truck, and I think I might have smacked it with the trailer a few times, lol.  

I just went out to check the box on the outside of the house, and found a bit of cluster, lol.  Feed cable coming in from underground, which feeds to a 3-way splitter.  Two of the legs goes to ports in the house, with the 3rd going to a 4-way splitter.  Two more of those legs going to house ports, one goes I don't know where, and the 4th is empty and unterminated  (Certified techs FTW! lol)  

The modem is currently on the 3 way splitter, on the leg marked 3.5db, with the other two legs marked 7db.  All the connections are tight from the modem back to the box.  I only have 3 of the cable ports actually being used right now, so I should be able to eliminate the 4 way splitter for now, though I'm not sure if it would affect the immediate problem.  I'll need to dig out my cable tester to determine which line is the one going from our house to the box on the street though.  

Sounds like the short of it though is that I do need to get Cox out to check the lines/signal strengths, as although the Cisco modem is working for now, I should be able to get a stable signal for the Motorola as well.  

Eric

[Page Radio Company]

Consider buying a replacement Surfboard from Best Buy and if it doesn't work any better, return it.

Dennis