Cable Modem signal levels...help

[mcchbib]

I recently had WOW 500M internet installed. i can get the full speed at times, but sometimes i have to attempt a download several times to get anything above ~100Kbps. These are the details of my cable modem status page:

Channel        Lock Status        Modulation    Channel        Frequency    Power        SNR        Corrected    Uncorrectables
1              Locked            256QAM        17          681.00 MHz    1.40 dBmV     38.98 dB    20627       36252
2              Locked            256QAM        12          561.00 MHz    5.10 dBmV     40.37 dB    2319         13638
3              Locked            256QAM        11          567.00 MHz    5.00 dBmV     40.95 dB    2112          17212
4              Locked            256QAM        10          573.00 MHz    5.20 dBmV     40.37 dB    2140         16028
5              Locked            256QAM        9           579.00 MHz    5.30 dBmV     40.37 dB    1067          11112
6              Locked            256QAM        8           585.00 MHz    5.20 dBmV     40.37 dB    1198           8702
7              Locked            256QAM        7           591.00 MHz    5.00 dBmV     40.95 dB    677             8477
8              Locked            256QAM        6           597.00 MHz    5.00 dBmV     40.37 dB    524             5716
9              Locked            256QAM        5           603.00 MHz    4.80 dBmV     40.37 dB    527             5900
10             Locked            256QAM        1           609.00 MHz    4.70 dBmV     38.98 dB    667             5300
11             Locked            256QAM        2           615.00 MHz    4.90 dBmV     40.95 dB    541             7521
12             Locked            256QAM        3           621.00 MHz    4.50 dBmV     38.98 dB    309             4597
13             Locked            256QAM        4           627.00 MHz    4.30 dBmV     38.98 dB    292             4371
14             Locked            256QAM        13          651.00 MHz    3.80 dBmV     38.98 dB    815            6280
15             Locked            256QAM        14          657.00 MHz    3.80 dBmV     38.98 dB    589            6276
16             Locked            256QAM        15          663.00 MHz    3.40 dBmV     38.98 dB    551            4771
17             Locked            256QAM        16          669.00 MHz    2.90 dBmV     38.61 dB    477            6621
18             Locked            256QAM        18          687.00 MHz    -0.80 dBmV    36.39 dB    1134           5291
19             Locked            256QAM        19          693.00 MHz    -2.90 dBmV    36.39 dB    1241           6714
20             Locked            256QAM        20          699.00 MHz    -0.90 dBmV    36.61 dB    4746           20351
21             Locked            256QAM        21          705.00 MHz    1.80 dBmV     38.61 dB    7936          53423
22             Locked            256QAM        22          711.00 MHz    3.60 dBmV     38.61 dB    1098          4461
23             Locked            256QAM        23          717.00 MHz    4.70 dBmV     38.98 dB    1242          5237
24             Locked            256QAM        24          723.00 MHz    5.20 dBmV     38.98 dB    1071          8645
25             Locked            256QAM        25          729.00 MHz    5.60 dBmV     39.50 dB    515            774
26             Locked            256QAM        26          735.00 MHz    6.50 dBmV     39.90 dB    191            1027
27             Locked            256QAM        27          741.00 MHz    7.10 dBmV     39.90 dB    258            803
28             Locked            256QAM        28          747.00 MHz    7.10 dBmV     39.20 dB    649            2206

The line from the service pole is about 25ft and enters my house. There is one 2-way splitter connected to the cable modem and nothing else is connected to the line. The line is new, the cable modem is new (tested a few). WOW had a line tech out as well as the area supervisor. In an attempt to solve the issue, they followed the line all the way down my street and replaced something that had water in it (maybe some filter?). The issue was worse before they did this but it still isn't resolved.

My cable modem event log shows a "No Ranging Response received - T3 time-out" error once every day or two.

From some research i did online, i've read that the Power signal should not have such a broad range (-2.70dB to 7.00dB). This should be within 3dB for all channels i believe.

Before i call them to come out again and waste more time, i would love some feedback on what the cause could be and what can be done about it.

Appreciate any thoughts

edit: not sure how to make a table here...will work on fixing this

 

[mindless1]

Some servers have per client bandwidth limits so everyone gets a slice of the pie. That seems like what you might be encountering but if it happens again, immediately do a speed test at speedtest.net or your ISP's speed test page.

Your power levels never drop below -2.9dBmV which is fine. They're usually fine down to -10dBmV or lower, though that low (-10dBmV) is usually a degraded line or just too many splitters on a line. I wouldn't worry about variances from each channel, just that none drop too low.

Your time-outs are probably some intermittent line fault in the neighborhood, harder to find because a tech has to be there at that moment to trace it. If the fault lasts long enough to effect your use of the service rather than just being in a log then it's closer to something they can trace. If a fault like that happens you will lose a download, not have it be only 100KB/s.

Wait, did you mean 100KBps or 100Kb/s? A normal server limit might be 100KB/s but not 100Kb/s which is too low. I would ignore that and do the speed tests on as many speed test servers as you can find, they go with the higher numbers to rule out internet congestion.

 

[gpse]

When the issue happens, ask them to check the speed on your neighbours connection. This will rule out if it's an area/neighbourhood issue, or something that only affects your connection. They should be able to check the speeds from there end over the phone, so it's good to call right when the issue happens.

If it only affects you, then it has to be something from the service drop to your modem.

 

[William Gaatjes]

What does corrected and uncorrectables mean ?
Are those the packets that have been corrected and dropped ?
Seems like an awful lot.

The line would be fine in gross speed but when looking at net data delivery when so many packets are dropped and need to be re transmitted, it would explain the low transfer speeds.
That is, if i interpret it correctly.
Seems as if there is something intermittendly interfering with the signal on the line maybe ?
Noise immunity problem ?

 

[VirtualLarry]

You might need a firmware update for that modem, is it one of the newer Docsis 3.1-capable models? There was an error with one of them with T3 timeout errors being a firmware issue. It could be your cable plant too, those 36dBm S/N ratios are right on the edge of what is necessary for Docsis 3.0 communication.

 

[Elixer]

If the system uses DOCSIS 3.0 they actually allow 3dB-6dB (maybe even higher) between adjacent channels.

Are all cable ends terminated?
You said you are using a 2 port splitter, but, what is feeding this line? Is there a amp someplace? Is this above or under ground?
Is it cold or hot there, does it change with outside temps?
Do you know how far away you are from the drop?

If this happens at specific times, it could also be a neighbor leaking into your line (or..or...or), but, they would need to send a line tech out, at exactly the time it happens.
So, keep logs of when this happens, then you can tell them to visit at that hour...and they can hopefully nail down the issue.

 

[mindless1]

You might need a firmware update for that modem, is it one of the newer Docsis 3.1-capable models? There was an error with one of them with T3 timeout errors being a firmware issue. It could be your cable plant too, those 36dBm S/N ratios are right on the edge of what is necessary for Docsis 3.0 communication.

Most info I've seen states Docsis 3.0 just needs 30dBmV or higher. 3/4ths of my channels are 36-37dBmV and I have no speed or intermittent connection issues.

 

[Fir]

Correcteds are OK but uncorrectables indicate a problem. Especially in higher numbers. It will affect the quality of streams in VOIP and increase jitter, etc.

 

[razel]

Agree with the splitter. If the other end is not connected to anything, I'd remove it.

 

[mindless1]

mcchbib did you ever get this resolved?

Although it's probably a cable modem or cable line issue, and your signal levels could be higher, don't overlook other factors.

For example a few days ago I had a speed issue and it turned out to just be a bad network cable. I had *disturbed* the cable fiddling with other wires behind a desk, and it worked fine after that, but a few weeks later the issue popped up, but even then it was intermittent, would maintain a connection but be terribly slow then pick back up again.

I did also have modem T3 time out errors every few days but it was just coincidental to the network cable fault.