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Low Upstream Power Levels causing delay?

I've been doing some research on this as i've had this problem for as long as i can remember, which i notice particularly on FIFA 20 (yes, I know there was a widespread issue but this is completely unrelated to that)

Long story short, I always get horrendous delay on this game. I know this can be an EA server issue, but this problem is very erratic and spontaneous so it's not i.e just during their peak hours, which can be common.

I avoid their peak hours and still I have this issue, which heavily leads me to believe this is an ISP issue

I spoke to a friend who's also with VM and had exactly the same problem, he recently had his issue fixed because it turned out he wasn't getting enough power to his house.. ever since then, no delay! I can't imagine

So i've checked up my Upstream power levels as follows:

Channel Frequency (Hz) Power (dBmV) Symbol Rate (ksps) Modulation Channel ID

1358000243.85512064 qam2
2537000093.85512064 qam4
3273999833.85512064 qam3
4458000023.85512064 qam1

 

After researching I've seen that the optimal range is between 4.4 and 4.6 (x10 because of the bug) for Upstream power levels, could this be the reason for why I'm suffering delay? My downstream power levels are fine, and within the recommended ideal.

If so, do I need a tech to fix this? Thank you.

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Alessandro Volta
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Re: Low Upstream Power Levels causing delay?

38.5 is a very good level, there is nothing for a technician to fix

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Re: Low Upstream Power Levels causing delay?

That really wasn't too helpful or true as it's exactly what fixed the same issue for my friend, his levels were 6 dB below the optimal range and it proved to be the difference once fixed.

This aside, I have also noticed I am not able to forward any ports. I'm using a Nighthawk R7800 with the SH3 in modem mode and upon checking canyouseeme - on the PS4 itself - the port isn't showing itself as open, simply "connection refused"

This happens with any port I try to forward, is there a known issue with this also? If so, is there a fix?

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Re: Low Upstream Power Levels causing delay?

Hello

I agree the power levels are fine, and certainly wouldn't affect the port forwarding if you want to have a  little bit of primer into power level see https://community.virginmedia.com/t5/Networking-and-WiFi/POWER-LEVELS-amp-SNR-A-TECHNICAL-PRIMER-upd... the second post is regarding the upstream which has a target of between 23 dBmv to 51 dBmv so basically looking at your power levels your in the middle.

Regards Mike

I dont work for VirginMedia all opinions are my own.
39 years in IT.
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Re: Low Upstream Power Levels causing delay?

Transmit level is about not getting packet loss (transmitting above the noise). If you don't have packet loss then your problem lies elsewhere.
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Re: Low Upstream Power Levels causing delay?

I do get very minor flakey packet loss, had multiple engineers look into it but there's nothing they can do as its to do with VM's underground materials (probably very aged, in need of an upgrade) - but I don't always experience delay, sometimes it is fine. Other times it is not - again not even during peak time - and there is nothing I can do but switch off and come back later.

I'm still not convinced on the upstream levels not being an issue, as the optimal range I saw, likewise for my friend's exact same issue would suggest

But the issue of not being able to successfully forward any ports, using an R7800 Nighhawk through the SH3 in Modem mode, could also be a problem causing this.

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Alessandro Volta
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Re: Low Upstream Power Levels causing delay?

Your upstream levels are better than normal, it's not an issue 

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Re: Low Upstream Power Levels causing delay?

We agree to disagree jb66.

That aside, I already mentioned but you missed out, port forwarding isn't working at all. Can anyone shed light on this?

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Re: Low Upstream Power Levels causing delay?


@patch22 wrote:

We agree to disagree jb66.

That aside, I already mentioned but you missed out, port forwarding isn't working at all. Can anyone shed light on this?


With the hub in modem mode, all it is doing is to send all incoming traffic directly to the WAN connection on the Nighthawk, so all the port forwarding is being done from that. You'll need to firstly make sure that the PS4 is listening on the correct ports, then check that the Nighthawk is forwarding the ports onto the private IP address of the PS4.

Now with regard to the upstream power levels, firstly there seems to be a bit of misunderstanding going on. In your very first post, you mention about your friend 'not getting enough power to his house', well that's downstream power not upstream. But if it was a typo and should have been not enough power from his house, then that also doesn't really make too much sense. The hub needs to send traffic back upstream to the internet, and to do that it has to send a signal out, through the coax cables out to the street cabinet. From there it may well pass through a number of daisy-chained cabinets before finally arriving at an optical node, where it gets sent down a fibre connection to the CMTS in a VM headend. The signal level when it gets to there needs to be at a certain level and above a certain signal to noise ratio to be properly understandable - none of these values can you see on the hub itself.

So the question is 'how much power does the hub need to put out to ensure that when the signal gets to the CMTS the signal is OK?' Well, imagine that you took the hub and were able to connect it directly to the optical node with no loss, then it would literally only need to be putting out about 15dBmV. Your home though might be many km away so the signal needs to leave the hub, pass through any splitters (there's an extra 3dB of attenuation to be overcome right there), get to the cabinet (how long is the cable, need to allow for the impedance of that?), then in the cabinet, you'll be connected to a tab point (15, 18, 22 etc extra dB attenuation there), then into an amp and up the chain to the next cabinet. When the hub first starts up, it tries to communicate with the CMTS at a very low power level and then ramps it up until a good connection is maintained and from that point the hub and CMTS exchange messages periodically so that the hub can adjust its power output if necessary. For example, the sun comes out and warms the cables up, they expand and increase the impedance, the power level drops at the far end so the hub has to increase output to compensate

Since you don't see any of this or know what's happening between the hub and the CMTS, all you can see is how much power the hub is putting out at that time to maintain a decent connection - you don't really want it to be too high as that is likely to introduce excessive noise, 57dBmV in total is about the highest the hub 3 will put out before the wheels drop off the wagon, so 57dBmV split across 4 channels (reduce by a factor of 4 is a reduction of about 6 dB) is where the oft quoted 51 dBmV come from.

Now this is a bit of an oversimplification but the point is that it's pointless trying to compare upstream power level with another user, unless they have exactly the same setup as you, cable lengths, number of splitters and the characteristics of all of these are identical to yours, and they live exactly the same distance from the street cabinet, and they're on the same tap impedance, and the number and performance of the amps between them and the optical node are the same, then you really won't see the same output power, there's far too many variables.

Anyhow TL:DR your upstream power levels are fine, if you have performance issue with gaming, it's far more likely to be upstream latency.

John

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Re: Low Upstream Power Levels causing delay?

Hello patch22

I have checked a few things from here and the upstream  signal levels are out of sync 

You were correct in saying that. 
You will need engineer to come out and take a look at things
I Will need to send you a private message to pass security first though 
If you are happy to go ahead with this just check the purple envelope top right of your screen 
Speak soon 
Gareth_L
 

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