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Standard User jelv
(knowledge is power) Wed 17-Mar-21 21:02:31
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Speedtest half speed upload using IPv6 and Firefox


[link to this post]
 
Could anyone make suggestions as to why this might be?

My Broadband Speed Test

My Broadband Speed Test

This is on a desktop using wired Ethernet.

I'm seeing similar results with other speed checkers, so it's not just a quirk of the tbb speed test.

However using different browsers (Chrome, IE and Edge tried) to run the tbb test all gave IPv6 uploads around 17-18Mbps as did a test run using the Android version of Firefox on my phone.

http://labs.thinkbroadband.com/speedtest/ sees a similar IPv6 50% upload speed reduction.

jelv

FTTC & Line rental: ZeN from March 2021

Previously: AAISP (November 2016 to March 2021) & Pulse8 line rental
Plusnet November 2001 to October 2016

Edited by jelv (Wed 17-Mar-21 21:08:52)

Standard User Pheasant
(experienced) Wed 17-Mar-21 22:04:42
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Re: Speedtest half speed upload using IPv6 and Firefox


[re: jelv] [link to this post]
 
Can you replicate on your net with another Windows box running Firefox?

My Broadband Speed Test
Standard User jelv
(knowledge is power) Wed 17-Mar-21 23:00:19
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Re: Speedtest half speed upload using IPv6 and Firefox


[re: Pheasant] [link to this post]
 
Yes - exactly the same. IPv4 Firefox OK, IPv6 Firefox slow, IPv6 Chrome OK.

As it's half my first though was packet fragmentation and MTU. But why would that only affect tests run using Firefox?

jelv

FTTC & Line rental: ZeN from March 2021

Previously: AAISP (November 2016 to March 2021) & Pulse8 line rental
Plusnet November 2001 to October 2016


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Standard User jelv
(knowledge is power) Wed 17-Mar-21 23:08:25
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Re: Speedtest half speed upload using IPv6 and Firefox


[re: Pheasant] [link to this post]
 
I've just looked back at speed test results in my profile and I have in the past had correct upload speeds using the same PC, Firefox and IPv6. However what has changed since:
  1. ISP
  2. Router
  3. Windows updated to 20H2
  4. Several Firefox updates


jelv

FTTC & Line rental: ZeN from March 2021

Previously: AAISP (November 2016 to March 2021) & Pulse8 line rental
Plusnet November 2001 to October 2016
Standard User Pheasant
(experienced) Wed 17-Mar-21 23:30:23
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Re: Speedtest half speed upload using IPv6 and Firefox


[re: jelv] [link to this post]
 
Given it’s solely affecting Firefox under windows in more than one machine, but not other machines (or other browsers on original machine) then I would be more inclined to look at the interaction of these updates:

3. Windows updated to 20H2
4. Several Firefox updates

My Broadband Speed Test
Standard User GonePostal
(committed) Wed 17-Mar-21 23:43:05
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Re: Speedtest half speed upload using IPv6 and Firefox


[re: jelv] [link to this post]
 
In reply to a post by jelv:
I've just looked back at speed test results in my profile and I have in the past had correct upload speeds using the same PC, Firefox and IPv6. However what has changed since:
  1. ISP
  2. Router
  3. Windows updated to 20H2
  4. Several Firefox updates


IDNet, Firefox Beta v87.0 64-bit, Windows 20H2, nominal 80/20 line and TBB speedtest recording 16+Mbps upload on both IPv4 and IPv6 whether logged in or as guest.
Standard User bob_lucas
(regular) Thu 18-Mar-21 09:32:46
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Re: Speedtest half speed upload using IPv6 and Firefox


[re: jelv] [link to this post]
 
That is interesting. I have been suffering various problems with my Internet connection and BT have changed my profile (reduced speeds have improved stability). However, that is a separate matter.

Recent tests indicated that upload speeds had declined disproportionally, so I have just performed a new series of tests, using Firefox 86.0.1 (64-bit) and Microsoft Edge Version 89.0.774.54 (Official build) (64-bit). The operating system is Windows 10 Home 20H2 (10.0.19042 Build 19042).

Today's tests revealed the same phenomenon. Upload speeds were 6.66 Mbps with Edge and only 1.77 Mbps with Firefox,

The latest Firefox update has also changed other settings, with an adverse effect upon the result, when it prints graphics from a web page...
Standard User jelv
(knowledge is power) Thu 18-Mar-21 10:19:42
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Re: Speedtest half speed upload using IPv6 and Firefox


[re: bob_lucas] [link to this post]
 
What router are you using? Mine is a Fritz box 7530.

I've seen some reports of printing issues following the latest Windows updates. A friend is finding that printing a full page pdf image the middle of the page is blank.

jelv

FTTC & Line rental: ZeN from March 2021

Previously: AAISP (November 2016 to March 2021) & Pulse8 line rental
Plusnet November 2001 to October 2016
Standard User bob_lucas
(regular) Thu 18-Mar-21 11:10:31
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Re: Speedtest half speed upload using IPv6 and Firefox


[re: jelv] [link to this post]
 
In reply to a post by jelv:
What router are you using? Mine is a Fritz box 7530.

I've seen some reports of printing issues following the latest Windows updates. A friend is finding that printing a full page pdf image the middle of the page is blank.

The router is a BT Smart Hub (Homehub 6).

I noticed the difference with printing, when I printed the additional diagnostics page from the BT Wholesale site at https://speedtest.btwholesale.com.

The results page shows two green and red bars, which compare actual results against the IP Profile for the line. Those bars appear on the screen and they were previously included in the print. But now, they are missing from the print, unless I select the "Print backgrounds" option. The page has heavy backgrounds, so that uses a lot more toner or ink.
Administrator seb
(founder) Thu 18-Mar-21 11:44:33
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Re: Speedtest half speed upload using IPv6 and Firefox


[re: jelv] [link to this post]
 
I'm not seeing v6 slowdown systematically on a 1Gbps connection (not getting full speed as on wifi).. it varies a bit but not consistent v4 vs v6 upload issues on MacOS + FF

Sebastien Lahtinen
[email protected]

The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User jchamier
(eat-sleep-adslguide) Thu 18-Mar-21 12:24:08
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Re: Speedtest half speed upload using IPv6 and Firefox


[re: bob_lucas] [link to this post]
 
In reply to a post by jelv:
Could anyone make suggestions as to why this might be?
I wonder if it is worth raising with Mozilla/Firefox support somehow?

In reply to a post by bob_lucas:
The latest Firefox update has also changed other settings, with an adverse effect upon the result, when it prints graphics from a web page...
Firefox 86 seems to have redesigned printing. The windows printing bug causes a full crash (BSOD); so you would know if you suffered from this. (I believe MS has pushed a fix for this already).

This thread is fascinating, I can't test as Virgin Media don't support IPv6.

21 years of broadband connectivity since 1999 trial - Live BQM

Edited by jchamier (Thu 18-Mar-21 12:25:11)

Standard User prlzx
(experienced) Thu 18-Mar-21 12:41:52
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Re: Speedtest half speed upload using IPv6 and Firefox


[re: jelv] [link to this post]
 
I don't experience the 50% reduction but I'm only on 40/10 so that doesn't necessarily help.
Tested using Firefox 86.0 (64-bit) on Lubuntu 20.04 on a wired connection over a Fritz!box 7530.

I would suggest it's unlikely to involve the router as for IPv6, it only needs to route at layer 3 (IP) rather than NAT where it needs to modify the source TCP port (and IP) on the way out, and match this established flow on the reply.
So other than any added firewall rules it does not need any awareness that it is even web traffic let alone which browser you are using.

On Firefox one troubleshooting step should involve creating a new profile with the defaults for that version and no add-ons (especially ones which do content filtering such as ad or tracker blockers).

On Windows some internet security products can cause traffic to appear as if processed more in bursts than at a steady rate; Kaspersky was one I would have to temporarily disable before network speedtests.

In the general case IPv6 tries to avoid fragmentation and makes that solely the responsibility of the endpoints to simplify the routers workload by not having to break up into / re-assemble from fragments on route.
This is combined with an increased of the minimum MTU from 576 to 1280, so even if an endpoint is unable to determine the PathMTU it can send at 1280 without fragmentation.
The % difference in overheads between 1280, 1400 (Cloudflare!) 1492 and 1500 is nowhere near enough to half the throughput so MTU can be dismissed without much consideration, unless you are tunneling IPv6 over IPv4 rather than native IPv6.



prlzx on Zen: FTTC (VDSL) at ~40Mbps / 10Mbps
with IP4/6 (no v6? - not true Internet)

Edited by prlzx (Thu 18-Mar-21 13:08:51)

Standard User GonePostal
(committed) Thu 18-Mar-21 13:15:48
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Re: Speedtest half speed upload using IPv6 and Firefox


[re: jchamier] [link to this post]
 
In reply to a post by jchamier:
In reply to a post by jelv:
Could anyone make suggestions as to why this might be?
I wonder if it is worth raising with Mozilla/Firefox support somehow?


Firefox support often involves quite a process of raising a bug through Bugzilla. There is a lot of unofficial help and support available through the Mozillazine Forums.
Standard User jelv
(knowledge is power) Thu 18-Mar-21 14:08:42
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Re: Speedtest half speed upload using IPv6 and Firefox


[re: seb] [link to this post]
 
I think it's a Windows only issue.

jelv

FTTC & Line rental: ZeN from March 2021

Previously: AAISP (November 2016 to March 2021) & Pulse8 line rental
Plusnet November 2001 to October 2016
Administrator seb
(founder) Thu 18-Mar-21 16:43:25
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Re: Speedtest half speed upload using IPv6 and Firefox


[re: jelv] [link to this post]
 
In reply to a post by jelv:
I think it's a Windows only issue.

Mmm ok... Will get Andrew to take a look smile

Sebastien Lahtinen
[email protected]

The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User AndrewNi
(member) Fri 19-Mar-21 11:28:23
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Re: Speedtest half speed upload using IPv6 and Firefox


[re: jelv] [link to this post]
 
I'm using Windows 10 1909 x64 with Firefox 86.0.1 (x64) and the upload is fine here. 20M up sync.

My Broadband Speed Test

Downstream is a bit slow for 63M down sync, but eh. There are several devices attached at the moment.
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