Comcast XFINITY → Do I have signal quality issues? Same "7-11pm degrading"...

I came to the forums this evening, trying to track down what the real source is of the problems that seem to come around every night on my cable modem - at about 7 or 8 pm, the service just becomes unusable. It stays that way until about midnight-ish... I'm not sure if it's DNS failures, general packet loss, or what ...

Interestingly enough, I work from home during the day - and the connection is rock-solid all day long. No issues at all.

I've tried switching my DNS on my router to use OpenDNS, without much help. I just read about the 4.2.2.x addresses here, so I'm trying those for now.

But I'm trying to read up on signal strength to understand my connection better. Based on the FAQ, I was reading that I should have a downstream strength of:

For all modems:
-10 dBmV to +10 dBmV "Recommended".
-11 dBmV to -14 dBmv / +11 dBmV to +14 dBmV "Acceptable".
-15 dBmV & +15 dBmV "Maximum".

But I'm noticing that my modem (a 2002 Scientific Atlanta) is reporting the following currently:

Receive Power Level
0.39 dBmV

Transmit Power Level
40.00 dBmV

At 0.39dBmV as its showing, the performance is actually acceptable right now. But not much more than an hour or two earlier this evening, it was down in the 0.20dBmV range ... and my connections were falling quite a bit. I don't know how to resolve the reading I see, against the recommended guidelines (that seem to be in the 10 to 15 range)?

Just for kicks, I'm going to build a logger to scrape the modem's status page for a few days, and see how much the signal varies. At least that might give me something useful to provide Comcast with, if they eventually have to roll a truck out here?

signal will vary with temperature....

That amount of variance you are seeing is insignificant. You are talking hundreths of a dB here.

The closer the DPL is to a perfect zero ( the exact middle of the range) the better.

Your issue sounds capacity related... Also sounds like you are probably off the Leesburg VA hub.. If your issue is time based like 7pm-11pm it's a capacity issue.

Ah, ok -- so a reading between 1.0 and 0.0, plus or minus, would actually be good?

He is right.. your levels are fine..

Probably. My IP currently resolves to:

c-75-75-18-xx.hsd1.va.comcast.net

so that might be it.

If that is off the Leesburg hub - I'm assuming it's a known problem that it is significantly oversubscribed?

Yes. It is the extremes of that range, plus + or minus - from zero that can result in connectivity problems.

Sterling Hub my friend...

Any better or worse than the Leesburg hub? The same?

I'll try to search the forum here a bit for those areas - see if I can find any references to similar problems.

I don't believe either sites have a capacity issue... It's possible you have something more isolated and local though.

sounds like a 7-11 noise issue, if not capacity.

would be curious to see if any others in the node, or blade are reporting problems similar

Well, I took my five year old Scientific Atlanta modem over to Comcast today for a swap. Figured maybe giving the modem an upgrade might help.

The good news? Now, my speeds are faster. The bad news? Comcast has been blinking offline every 5-10 minutes all day, with either modem ... the Scientific Atlanta, or the Terayon I just got.

Is the Terayon decent in terms of reliably holding a signal? Should I have asked to see if they had another type in stock? I just took what they gave me...

Hopefully it was just something with the neighborhood today ... because it was basically unusable all day today.

Have you ran a line quality check from here for packet loss? I had a similar problem about a year ago which turned into a 3 month headache requiring me to climb the ladder ultimately to the executive complaint department. Had serious packet loss.

Doesn't look like things are getting much better. Overnight, when everyone in the house was asleep - I can see from the router logs that the WAN interface was still dropping every few hours and resetting itself... I have an entry like this every hour or two, all night:

[INFO] Tue Nov 06 02:05:18 2007 WAN interface is down
[INFO] Tue Nov 06 02:05:18 2007 WAN interface cable has been disconnected

I have this same 'WAN interface is down' and 'WAN interface cable has been disconnected' problem ... can anyone shed light on what this is and how to stop it?

I have a DLink 655 Wireless N router.

-Gina

I can't speak for all modems, but a user-initiated (or CMTS-initiated) reboot on my SB5120 will take down and back up the ethernet link. It doesn't happen when the modem loses sync and reconnects without a reboot.

Jan 22 04:43:20 xxx kernel: fxp0: link state changed to DOWN
Jan 22 04:43:22 xxx kernel: fxp0: link state changed to UP

I think CCguy is right with the noise on the return....a few things though......

1. What is your downstream Signal to noise ratio..(SNR)....Your can have perfectly fine level and the quality be complete crap.

2. Are you home all day? Is 7-11 p.m. the only time its happening throughout the day or is it the only time of the day you normally use it.

3.If it is noise on the return having service techs come to your house isn't going to yeild much other than a referral to maintenance which is who is going to have to fix that.

Wonder if the O.P. will return ?