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Tetrako's avatar
Tetrako
Joining in
30 days ago

Router levels unstable - Do I need a callout?

As of recently, I've noticed my router's downstream power levels are reaching too high a point, while my upstream modulations are now consistently flipping between 16QAM, 32QAM and 64QAM. I've checked all my connections and restarted my router a couple of times, but this makes no difference. So far, the only tangible issue from this has been my upload rate dropping in the evenings to sub 5mbps and affecting voice calls and my own personal streams but I have reason to believe soon enough my downstream connection will experience issues too due to the high power levels.
I took these readings on the night of 30/03/2025 and the morning of 01/04/2025:

30/03/2025 22:00 -
Downstream bonded channels
Channel    Frequency (Hz)    Power (dBmV)    SNR (dB)    Modulation    Channel ID
1    139000000    16.9    38    256 qam    1
2    147000000    16.6    38    256 qam    2
3    155000000    16.5    38    256 qam    3
4    163000000    16.3    38    256 qam    4
5    171000000    16.1    38    256 qam    5
6    179000000    15.9    38    256 qam    6
7    187000000    15.9    38    256 qam    7
8    195000000    15.6    38    256 qam    8
9    203000000    15.5    38    256 qam    9
10    211000000    15.3    38    256 qam    10
11    219000000    15.3    38    256 qam    11
12    227000000    15    38    256 qam    12
13    235000000    14.9    38    256 qam    13
14    243000000    14.5    38    256 qam    14
15    251000000    14.4    38    256 qam    15
16    259000000    14.6    38    256 qam    16
17    267000000    14.6    38    256 qam    17
18    403000000    15.1    38    256 qam    34
19    411000000    15.1    38    256 qam    35
20    419000000    15.1    38    256 qam    36
21    427000000    15    38    256 qam    38
22    435000000    14.8    38    256 qam    39
23    443000000    14.5    38    256 qam    37
24    451000000    14.6    38    256 qam    40


Downstream bonded channels
Channel    Locked Status    RxMER (dB)    Pre RS Errors    Post RS Errors
1    Locked    38.6    8    0
2    Locked    38.9    24    0
3    Locked    38.6    26    0
4    Locked    38.9    24    0
5    Locked    38.9    27    0
6    Locked    38.9    28    0
7    Locked    38.6    11    0
8    Locked    38.9    16    0
9    Locked    38.6    11    0
10    Locked    38.6    16    0
11    Locked    38.6    10    0
12    Locked    38.6    10    0
13    Locked    38.9    12    0
14    Locked    38.6    21    0
15    Locked    38.9    21    0
16    Locked    38.9    17    0
17    Locked    38.6    18    0
18    Locked    38.6    10    0
19    Locked    38.6    26    0
20    Locked    38.9    25    0
21    Locked    38.6    15    0
22    Locked    38.9    29    0
23    Locked    38.9    12    0
24    Locked    38.9    22    0

Upstream bonded channels
Channel    Frequency (Hz)    Power (dBmV)    Symbol Rate (ksps)    Modulation    Channel ID
1    36599791    33.5    5120    32 qam    9
2    43100077    33.7    5120    16 qam    8
3    49600182    33.8    5120    16 qam    7
4    23599932    32.5    5120    16 qam    11
5    30099327    32.7    5120    16 qam    10


Upstream bonded channels
Channel    Channel Type    T1 Timeouts    T2 Timeouts    T3 Timeouts    T4 Timeouts
1    ATDMA    0    0    0    0
2    ATDMA    0    0    0    0
3    ATDMA    0    0    0    0
4    ATDMA    0    0    0    0
5    ATDMA    0    0    1    0

-----
01/04/2025
Downstream bonded channels
Channel    Frequency (Hz)    Power (dBmV)    SNR (dB)    Modulation    Channel ID
1    139000000    16.8    38    256 qam    1
2    147000000    16.5    38    256 qam    2
3    155000000    16.4    38    256 qam    3
4    163000000    16.3    38    256 qam    4
5    171000000    16    38    256 qam    5
6    179000000    15.9    38    256 qam    6
7    187000000    15.8    38    256 qam    7
8    195000000    15.5    38    256 qam    8
9    203000000    15.4    38    256 qam    9
10    211000000    15.1    38    256 qam    10
11    219000000    15.3    38    256 qam    11
12    227000000    15.1    38    256 qam    12
13    235000000    14.9    38    256 qam    13
14    243000000    14.5    38    256 qam    14
15    251000000    14.4    38    256 qam    15
16    259000000    14.5    38    256 qam    16
17    267000000    14.5    38    256 qam    17
18    403000000    15    38    256 qam    34
19    411000000    15.3    38    256 qam    35
20    419000000    15.1    38    256 qam    36
21    427000000    15    38    256 qam    38
22    435000000    15.1    38    256 qam    39
23    443000000    14.6    38    256 qam    37
24    451000000    14.6    38    256 qam    40


Downstream bonded channels
Channel    Locked Status    RxMER (dB)    Pre RS Errors    Post RS Errors
1    Locked    38.6    9    0
2    Locked    38.9    31    0
3    Locked    38.6    30    0
4    Locked    38.9    28    0
5    Locked    38.6    39    0
6    Locked    38.9    30    0
7    Locked    38.6    13    0
8    Locked    38.6    19    0
9    Locked    38.9    18    0
10    Locked    38.6    23    0
11    Locked    38.6    17    0
12    Locked    38.9    21    0
13    Locked    38.6    16    0
14    Locked    38.6    27    0
15    Locked    38.6    28    0
16    Locked    38.9    26    0
17    Locked    38.9    20    0
18    Locked    38.9    18    0
19    Locked    38.6    37    0
20    Locked    38.9    32    0
21    Locked    38.9    20    0
22    Locked    38.9    34    0
23    Locked    38.9    27    0
24    Locked    38.6    30    0

Upstream bonded channels
Channel    Frequency (Hz)    Power (dBmV)    Symbol Rate (ksps)    Modulation    Channel ID
1    36600000    34.5    5120    16 qam    9
2    43100000    34.5    5120    16 qam    8
3    49600000    34.8    5120    16 qam    7
4    23600000    33.2    5120    16 qam    11
5    30100000    32.8    5120    64 qam    10

Upstream bonded channels
Channel    Channel Type    T1 Timeouts    T2 Timeouts    T3 Timeouts    T4 Timeouts
1    ATDMA    0    0    0    0
2    ATDMA    0    0    0    0
3    ATDMA    0    0    0    0
4    ATDMA    0    0    1    0
5    ATDMA    0    0    1    0

 

12 Replies

  • Client62's avatar
    Client62
    Alessandro Volta

    Figures look like a 10dB attenuator has been removed from the coax cable to the VM Hub.

    Unless there is a known fault, an engineer will be required to corrects the signal levels.

    • Tetrako's avatar
      Tetrako
      Joining in

      We haven't removed any attenuators since it was first fitted. I did a power cycle a couple of nights ago and checked all cables were properly fastened and everything looked fine.

  • unisoft's avatar
    unisoft
    Knows their stuff

    You'll have issues with those downstream  power levels.  Opposite, Your upstream has low figures normally indicating you are near a VM cabinet and short cable run?

    If your cable run is short to the cab, the engineer normally needs to put you on a higher attenuated tap, which will raise your upstream levels to prevent cmts/cab screaming at the hub. 38 to 51 are the usual range for upstream. An attenuator may still need to be fitted to back of the hub too to reduce downstream if moving tap point isn't enough to bring it down within range.

    You aren't on a hub using docsis 3.1 channels, so attenuator is what's required. If you were using a hub4 or hub 5 that utilise docsis 3.1, then an equaliser would be used to prevent attenuation of the weaker frequencies used for docsis 3.1 channels.

    After this, everything should be OK unless you have burst noises causing the QAM levels to fluctuate.

  • I'd also like to add on now that I've noticed this seems to be a problem only around evening times. The upload rate in the day time seems to reach 50mbps just fine, and the QAM levels seem to get to 64 well enough but once we hit around 5pm-6pm, that's when the upload plummets.

  • Client62's avatar
    Client62
    Alessandro Volta

    A Downstream power level of 0 dBmV is perfect and this is a logarithmic scale.

    The crazy high Downstream power levels do need to be addressed.

    Phone  VM to request an engineer visit.

  • I cannot use the phone to contact due to hearing difficulties but trying the live chat unfortunately left me waiting for an hour and a half before the chat was promptly closed on me so I suppose I'll need to try again tomorrow morning and deal with this instability for another day.

  • Just as reference, this morning, this is now our upstream status and the upload rate is now fine:

    Upstream bonded channels

    ChannelFrequency (Hz)Power (dBmV)Symbol Rate (ksps)ModulationChannel ID
    13660000033.3512064 qam9
    24310000033.5512064 qam8
    34960000033.8512064 qam7
    42360000033.2512016 qam11
    53010000032.8512064 qam10



    Upstream bonded channels

    ChannelChannel TypeT1 TimeoutsT2 TimeoutsT3 TimeoutsT4 Timeouts
    1ATDMA0000
    2ATDMA0000
    3ATDMA0000
    4ATDMA0010
    5ATDMA0010
    • Tetrako's avatar
      Tetrako
      Joining in

      However, this will likely drop back down to 16 QAM in the evening and our upload will plummet again.

  • And now, past 19:00:

    Upstream bonded channels

    ChannelFrequency (Hz)Power (dBmV)Symbol Rate (ksps)ModulationChannel ID
    13660008933.7512016 qam9
    24309910733.7512016 qam8
    34960000034512032 qam7
    42360025532.7512016 qam11
    53010014933.2512016 qam10
  • An update now:

    Got in touch with VM live chat yesterday morning, and was issued a new router. Was sent another Hub 3 (with an incorrect power supply which I've packaged back up with the old Hub for return) and checked my router levels after the new kit was activated. To my lack of surprise, the downstream levels are still too high (17.5 dBmV at highest) and the upstream modulation is still dropping in the evening, causing upload rate to plummet to unusable levels.

    • Adduxi's avatar
      Adduxi
      Very Insightful Person

      A new Hub will not magically fix power levels.  They are too high on the DS and too low on the US.  A VM technician will need to sort this out for you. 

    • Tom_W1's avatar
      Tom_W1
      Icon for Forum Team rankForum Team

      Hi Tetrako thanks for posting although we're sorry to hear of the concerns you've raised here.

      Looking into this we can see that some of the power levels to the Hub are out of the required specifications, so let me send you a PM so I can investigate this further and respond directly when you can!

      Many thanks