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Amithyel's avatar
Amithyel
Tuning in
26 days ago
Solved

DOCSIS 3.1 ISSUE

Since the complaints section is effectively disabled on the website, and customer service does not understand what I am talking about at all, I am trying to reach the technical team through this message.

Please treat this as a technical case rather than a basic connectivity issue, and respond accordingly. I am happy to provide further diagnostic screenshots if required.

I am currently subscribed to your 1 Gbps broadband plan + Volte boost (1.2 Gbps), but the maximum achievable speed on my line remains around 930 Mbps. I have conducted a detailed technical investigation and found that, although my modem is configured for DOCSIS 3.1, it continues to operate in DOCSIS 3.0 mode due to severe signal quality issues.

Summary of the technical findings:
DOCSIS 3.1 is detected but not actively bonded.
Modem status confirms:
31 downstream / 5 upstream DOCSIS 3.0 channels are active (QAM256).
1 downstream / 1 upstream DOCSIS 3.1 channel detected, but not functional.

The DOCSIS 3.1 downstream channel (Channel ID: 41) reports:
PLC Power: -23.4 dBmV (far below acceptable range of -7 to +7)
RxMER: 26 dB (borderline for QAM4096)
Corrected Errors: 3,101,730,52+
Uncorrectable Errors: 3,186,089,505+

These extreme error rates and severely degraded power levels render the DOCSIS 3.1 OFDM channel unusable. As a result, the modem is falling back to DOCSIS 3.0 — which is inherently limited to sub-gigabit speeds in practical use. The DOCSIS 3.1 channels are locked, but not stable or healthy enough to be used for active traffic.

I am requesting the following actions from Virgin Media:
Escalate this issue to a senior technical engineer who understands DOCSIS 3.1 channel bonding and RF impairments.
Investigate and resolve the underlying signal quality issues that are causing the DOCSIS 3.1 PLC to fail — including possible ingress noise, upstream distortion, or line faults.
Rebalance the line or inspect external cabling/equipment contributing to signal degradation.
Ensure that the modem is able to operate in full DOCSIS 3.1 mode with proper OFDM channel bonding.
Confirm once full DOCSIS 3.1 operation is restored and my service can achieve the contracted 1.2 Gbps throughput.

Please treat this as a technical case rather than a basic connectivity issue, and respond accordingly. I am happy to provide further diagnostic screenshots if required.

Thanks

#DOCSIS
#DOCSIS 3.1
#Gig1
  • carl_pearce's avatar
    carl_pearce
    26 days ago

    There is only one 2.5Gbps ethernet port on the HUB 5, are you using it?

    And yes, you can't 'boost' above Gig1. So, if you were already on Gig1 Volt will not boost you further.

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  • carl_pearce's avatar
    carl_pearce
    Superstar
    26 days ago

    Just a note there is no such thing as a boost from 1Gbps to 1.2Gbps. It's probably a M500 subscription Volt boosted to Gig1, which is 1130 - 1150Mbps.

    The below site will confirm the speed to the HUB over the VM network, as well as the speed to the device:

    https://samknows.com/realspeed/

    Just keep in mind the maximum speed you'll see to one wired device is 940Mbps, unless it has a 2.5Gbps ethernet adapter, and it's connected to the only available 2.5Gbps ethernet port, assuming you have a HUB 5.

    You can check for local issues:

    https://www.virginmedia.com/help/check/status

    One other thing to consider is VM are supplying over the min speed guaranteed, although it's outside the 'expected' range:

    https://www.virginmedia.com/broadband/our-speeds-explained

     

    • Amithyel's avatar
      Amithyel
      Tuning in
      26 days ago

      Hi,
      The contract is 1Gig+Volte boost.  Not M500. Additionally, the speed was tested using a 5 Gbps Ethernet adapter and a 2.5 Gbps Ethernet adapter, as well as on two high-end desktops.
      Cable is a high-speed professional Ethernet cable (CAT 8), 40 Gbps, 2000 MHz, Gigabit cable.
      The only issue could be if the Hub 5 port only supports up to 1 Gbps. 
      There is no issue in my area.

      I've been with Virgin for years, I don't need the explanation site. Thanks

      I didn’t upgrade and pay for this just to get less, simply because they can’t solve it technically.

      • carl_pearce's avatar
        carl_pearce
        Superstar
        26 days ago

        There is only one 2.5Gbps ethernet port on the HUB 5, are you using it?

        And yes, you can't 'boost' above Gig1. So, if you were already on Gig1 Volt will not boost you further.

    • Amithyel's avatar
      Amithyel
      Tuning in
      26 days ago

      The site can't submit any complaint because there is no option to choose in the second dropdown menu. Literally useless.

      • Martin_N's avatar
        Martin_N
        Icon for Forum Team rankForum Team
        23 days ago

        Hi Amithyel,

        Thank you for your post. We're very sorry to hear about the issue with your broadband service. 

        To confirm, is that speed showing on Samknows when a test is run?

        ^Martin