Broadband problem

I've been with Comcast (S. Calif) for about 3 years using the USR "shark fin", and I've been using the Motorola 5120 for about 10 months with not a single problem from either of them. What kind of modem do you have and does it have clearance on all sides for convective cooling? Tell us the modem, and someone here might be able to tell you how to read its web page. In all likelyhood, though, the problem is not the modem.

*TimDaniels*

Tim ,

The Modem I have is a SurfBoard Sb3100 . I keep in an open space behind my TV . It has air to breathe . bV

What did support say beyond "seems like"? Did they check anything or was it just "the modem is the problem" without checking, or with little explanation?

Is this a house, condo, apartment?

I can't speak to Comcast, but you will find an answer. It's taking me awhile to accept a dumb/passive device could go bad.

-- Oren

"Well, it doesn't happen all the time, but when it happens, it happens constantly."

I can't verify this from my own experience, but a cable tech. once told me that temperature changes, from the high of the day to the low, can cause the signals in coax cables to vary by a few dB (but I forget which has the higher signal loss). If your upstream or downstream signal levels are marginal even when things are working, then perhaps they go out of range when it's cooler in the mornings. -WBE

What are your RF readings from the modem's status page ?

TVs are plain hot in back esp. up top where they vent. Try moving at least 3 feet away from the TV, but it's probably not the TV unless it's plasma.

If you're renting, I'd be looking to upgrade to a DOCSIS 2 modem - your modem is older than many of the active poster's kids. :)

I have my modem on the floor while my TV is well up on a stand .There are five indicator lights on the modem . In the morning , the lights for ON and RECEIVE come on , then progressively SEND and then Online and Activity . Then the activity begins slow ( pages on the internet download slowly) and then great later in the day . It would almost seem that there is little coming through early in the day or that 100,000 people in the north end of Fall River ( pop 93,000 ) are all on the line at once but Comcast support said there was no problem in Fall River . This has been going on for three weeks . They checked my modem activity and said that there were outages mostly in the AM . I said no to a house call because I don't believe it's a modem problem .BV

What are the signal power levels, etc., from the modem web page at

192.168.100.1 ? Q

Here is the cut and paste of the current reading for 4:37 PM Wednesday Fall River Time when all is going well . BV

Downstream Value Frequency 693000000 Hz Locked Signal to Noise Ratio 28 dB Power Level 0 dBmV The Downstream Power Level reading is a snapshot taken at the time this page was requested. Please Reload/Refresh this Page for a new reading

Upstream Value Channel ID 4 Frequency 35600000 Hz Ranged

Power Level 50 dBmV

...

That SNR seems a bit low, particularly with such a high downstream power level. In any case, the important thing is to look again late tonight or in the morning BEFORE it loses sync/reboots/whatever it does that takes it offline (since the signal levels are meaningless once it's offline, if the cable modem's web server will talk to you at all). -WBE

[I already mentioned possible temperature, and thus time-of-day, effects on coax in article .]

Not the greatest set of numbers. Tx power would be nicer below 50 and SNR should be over 30 and would be nicer in the high 30's.

I still think that old DOCSIS 1 modem would be the first thing to swap out after verifying the cabling is all good. Maybe swap with a neighbor and see what your numbers are.

How about a drawing of your cabling ? Are your connections tight ? Are you using RG6 cable ? How many splitters and type ?

Here's an eg from my house :

/-- Grounding block pass thru connector | | RG6 Terayon Netgear PC1 PC2 | /------> TJ715 Modem ----> RP614 Rtr ------|---|---|---| RG6 V RG6 /

--------->X----->X to Family Room | RG59 |-----------------> BR1 TV | RG59 \\-----------------> BR2/3 TV (terminated)

My cable comes into the house to my second story suite and in my room , there is a splitter - one cable goes to the Tv and one to the cable modem .

I am actually getting very very slow internet this morning and the Signal to Noise Ratio has gone down to 26 db downstream and the power level also down to 49 dBmV upstream .

You only answered one Q - how do you expect to get decent help when you ignore the rest ?

That's a terrible SNR. The 50 going down to 49 isn't much improvement, but at least it's below 50. Mine's pretty high at 48 too.

You really do have an old modem--my installation was 6 years ago and it was a SB4100, eventually upgraded to a 4200 and now to a 5120 to take advantage of the new higher speed offered by my provider(Cablevision). I don't know about Comcast's policies but with Cablevision, if there is a modem (or modem related) problem they let you bring your old one to the nearest Cablevision center and exchange it for a new one at no charge. If there is no center nearby they will come and replace it. So why not try a newer model--what do you have to lose?

Ken

BV wrote:

Just bought a new modem and will install it later today . I will give progress reports . I'm sorry if I haven't answered all the questions but I am not very technical and I wasn't sure what I was being asked . Sorry . BV