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DOCSIS 3.1 and 4096 QAM attenuation - technical question

ST4
Tuning in

I have recently had a problem. 

I upgraded my M500 to 1GB and am not getting any think like the speeds that I should and am just getting over 535mb

Strangely my upload speeds are 50 to 52mb so in the right provisioning band for 1GB product and they if I am correct in my thinking on DOCSIS 3.0 (and the D/L on 3.1) 

I have had two engineer visits and still no further on, equipment and FTTP are okay

I am using a HUB4 which has been changed, but no change in speeds.

The provisioning appears to be correct and the levels are ok

My question is this, has anyone got a HUB4 with a wideband -3db attenuator that is getting 1GB+ 

On rebooting my Hub4  the QAM starts at 4096 and within 20 minutes drops to 2048, my speeds never seem to go above 550mb(measured direct at the HUB with 1GB nic and cat6 cable. (this happens with or without the attenuator in place)

I have ruled out everything else and am coming to the conclusion that it might be something with the attenuator or a miss match from the cabinet. 

Unfortunately there is no one else on my cabinet on 1GB so can't even find out if it is a local issue which is starting to get frustrating

Any help or idea appreciated

29 REPLIES 29

jb66
Very Insightful Person
Very Insightful Person

Are you testing using the samknows real speed website?

we have tested with the engineers handheld test meter and a clean boot linux / windows installations all showing the same results +/- 5mb directly to the rear of the modem
Sam knows does not work in modem only mode


@ST4 wrote:
we have tested with the engineers handheld test meter and a clean boot linux / windows installations all showing the same results +/- 5mb directly to the rear of the modem
Sam knows does not work in modem only mode

I have a 10dB Forward Path Attenuator fitted to reduce my downstream power levels, and I'm on Gig1, so you should be able to rule that out.

So just to confirm are you saying that the engineers couldn't get more than 550Mbps on their test kit?

yes, the speed tests were all agreeing with each other..

Is your attenuator a wideband one ?


@ST4 wrote:

yes, the speed tests were all agreeing with each other..

Is your attenuator a wideband one ?


so a bit of further reading

Attenuator - a plain attenuator will weaken (attenuate) all frequencies, reducing the downstream signal strength, and causing the upstream power to increase (the modem needs to "talk" louder).

Forward path attenuator - weakens (attenuates) the high frequencies used for downstream only, without affecting the upstream frequencies.

att2.jpg

 

wonder if this is the problem ?

Open to suggestions

 

legacy1
Alessandro Volta

Maybe VM have a router doing rate limiting somewhere.

is your Max Traffic Rate in hub settings showing the correct value?

have you tested without your router and have tested with PC to the hub in modem mode?

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jbrennand
Very Insightful Person
Very Insightful Person
I dont think you have said - are you testing on wifi or ethernet connections?

The Hub4 is wifi5 and so will never get above ~600Mbps on a single device - you need a wifi6 router for more than that.

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John
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I do not work for VM. My services: HD TV on VIP (+ Sky Sports & Movies & BT sport), x3 V6 boxes (1 wired, 2 on WiFi) Hub5 in modem mode with Apple Airport Extreme Router +2 Airport Express's & TP-Link Archer C64 WAP. On Volt 350Mbps, Talk Anytime Phone, x2 Mobile SIM only iPhones.

yes the max rate is showing provisioned okay all figures have been taken direct from the VM Hub 4