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Ghostly
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Message 1 of 7

Low BandWidth, High Speed

The connection is perfectly normal but when Netflix is turned on the ability to load webpages or game becomes impossible.

Capture.PNG

I'm guessing every time it sends data, it lags the whole network and I am unable to do anything. The speed does not change however I still get like 5MB/S down and 6.5mps upload.

The PC I use is on ethernet, I've tried turning Netflix to ethernet and wireless. we have received a new home hub and I've reset it a couple of times but nothing has fixed the issue.

This issue has appeared about 2 weeks ago, it's frustrating because it wasn't like this before and it suddenly happened.

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Keith_Beddoe
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Message 2 of 7

Re: Low BandWidth, High Speed

Welcome to this user forum.

This has been posted many times.

Here is one thread  https://community.bt.com/t5/Home-setup-Wi-Fi-network/Terrible-latency-whilst-gaming/m-p/1927860#M161...

I suspect that its the fact that Netflix, as well as downloading data, also seems to upload data in a number of regular blocks. This will affect network response times. TCP ACKs are quite normal, but Netflix seems to queue as many as possible, before uploading them.

I have seen this on a network analyser, but it may be better explained by someone with a better understanding of TCP IP. I think its called ACKs aggregation

@TimCurtis  may be able to explain it better, but I have seen the effect on Wireshark captures.

Whether they have changed their networking protocols recently, is difficult to say, but there are loads of other reports affecting multiple ISPs.

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Keith_Beddoe
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Message 3 of 7

Re: Low BandWidth, High Speed

Interesting article here, its a few years old now, but I suspect the problem is now worse.

https://arstechnica.com/information-technology/2014/11/netflix-takes-up-9-5-of-upstream-traffic-on-t...

Controlling the upload rate, by using a different router, may help. Some people have limited sucess with this.

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Keith_Beddoe
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Message 4 of 7

Re: Low BandWidth, High Speed

I am wondering if this is just an issue with VDSL "fibre" connections, in the way that connections are aggregated within the cabinet, which is causing buffering on the upload path?

I have an ADSL connection which gets about 9Mbs download speed, and 800Kbs upload speed, and I can see no change in the ping response when Netflix is running, even on a HD stream.

I am not using a home hub, so I do have full control of priority and bandwidth usage, which is very useful on an ADSL connection.

I did make a suggestion to another forum member, that they reduce the Netflix resolution to SD instead of HD, as that should also reduce the usage on the upload path.

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TimCurtis
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Message 5 of 7

Re: Low BandWidth, High Speed

It was very nice of @Keith_Beddoe to think I might know more about this but alas I don't.

Is it just Netflix that causes this , not things like BBC iPlayer (in HD) or downloads , like getting an image file for Windows or similar?

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Keith_Beddoe
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Message 6 of 7

Re: Low BandWidth, High Speed

@TimCurtis 

I may have confused you with another forum member that has experience with TCP/IP, which is an area that I do not know that much about, having worked on networking before the days of the Internet.

It would be interesting to know whether anyone who is on ADSL, is having the same problem, as I believe it just an issue with VDSL connections, and the way that the customer connections are multiplexed over a common fibre bearer, instead of having an individual connection into the core 21cn network, as in the case of ADSL.

Netflix seems to be the main cause of this issue, and has been reported elsewhere. Providers concentrate on getting good download speeds, and do not expect applications to upload much in the way of data, which I think is being buffered somewhere.

The BBC iPlayer does not seem to do things the same way, and sends its TCP ACKs more regularly, along with some other performance stats, which cannot be seen anyway, as they are sent HTTPS.

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Keith_Beddoe
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Message 7 of 7

Re: Low BandWidth, High Speed

What I have suggested before to people, is to use a router which has the ability to control both the download and upload priority and speed.

Then make sure that the device that is being used to stream Netflix, is given the lowest priority, and the minimum download bandwidth to give a acceptable picture. At the same time, restricting the upload bandwidth to the lowest possible, that avoids buffering due to the Netflix servers not seeing the ACKs.

I would be surprised if Netflix did not already have a mechanism for dealing with slow upload rates, as people can use Netflix on ADSL MAX, which only has a maximum upload speed of about 300Kbs or less, so restricting the upload speed on VDSL, should not be an issue, and would allow other applications, like games, to be able to send their commands to their servers, without being delayed.

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