Kitz Forum

Broadband Related => FTTC and FTTP Issues => Topic started by: sceptre on September 13, 2021, 01:00:55 PM

Title: Am I being capped?
Post by: sceptre on September 13, 2021, 01:00:55 PM
Hi all,
I am on a 80/20 service with Plusnet.  Historically I have been able to have stable speedtests of 70ish/17-19down but recently I'm only getting 35 down - it feels like I'm being capped and I don't know why!

I'm using an HG612 3B (and have been since using fibre), linked to my Unifi USG.

I've pulled some stats from the HG612 but not too sure what to make of them.    Can anyone advise ?  Thanks.  (Or if there are stats that I can get to help)

Code: [Select]
# xdslcmd info --vendor
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Last initialization procedure status: 0
Max: Upstream rate = 30744 Kbps, Downstream rate = 92836 Kbps
Bearer: 0, Upstream rate = 20000 Kbps, Downstream rate = 79999 Kbps
Bearer: 1, Upstream rate = 0 Kbps, Downstream rate = 0 Kbps
ChipSet Vendor Id: BDCM:0xc190
ChipSet VersionNumber: 0xc190
ChipSet SerialNumber: Q10K9000767_53
#

Code: [Select]
# xdslcmd profile --show

Modulations:
G.Dmt Enabled
G.lite Disabled
T1.413 Disabled
ADSL2 Enabled
AnnexL Disabled
ADSL2+ Enabled
AnnexM Disabled
VDSL2 Enabled
VDSL2 profiles:
8a Enabled
8b Enabled
8c Enabled
8d Enabled
12a Enabled
12b Enabled
17a Enabled
30a Enabled
US0 Enabled
Phone line pair:
Inner pair
Capability:
bitswap On
sra On
trellis On
sesdrop Off
CoMinMgn Off
24k On
phyReXmt(Us/Ds) Off/On
TpsTc AvPvAa
monitorTone: On
dynamicD: On
dynamicF: Off
SOS: On
Training Margin(Q4 in dB): -1(DEFAULT)
#

Code: [Select]
# xdslcmd info --stats
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Last initialization procedure status: 0
Max: Upstream rate = 30744 Kbps, Downstream rate = 92836 Kbps
Bearer: 0, Upstream rate = 20000 Kbps, Downstream rate = 79999 Kbps
Bearer: 1, Upstream rate = 0 Kbps, Downstream rate = 0 Kbps
Link Power State: L0
Mode: VDSL2 Annex B
VDSL2 Profile: Profile 17a
TPS-TC: PTM Mode(0x0)
Trellis: U:ON /D:ON
Line Status: No Defect
Training Status: Showtime
Down Up
SNR (dB): 6.9 15.8
Attn(dB): 11.9 0.0
Pwr(dBm): 13.3 -1.1
Title: Re: Am I being capped?
Post by: mofa2020 on September 13, 2021, 01:14:51 PM
Your line sync. is normal 79999 D and 20000 U so there is no sync. cap on the line, though the slower speed other Kitzens would help better.
Title: Re: Am I being capped?
Post by: sceptre on September 13, 2021, 01:35:03 PM
Your line sync. is normal 79999 D and 20000 U so there is no sync. cap on the line, though the slower speed other Kitzens would help better.

Thanks.
So if line sync is OK, would suggest issue between HG612 and the USG?  There's only a short ethernet cable between them which hasn't changed but I guess could be faulty.
Otherwise, I'll start investigating on the USG side of things.
Title: Re: Am I being capped?
Post by: RealAleMadrid on September 13, 2021, 02:31:42 PM
The link between the HG612 and the router is a 100Mbs ethernet connection so unlikely to be a problem. I assume you must be on Plusnet's Fibre Extra product to get the full 80/20 sync speeds.

Have you got a static WAN IP address, normally you pay Plusnet 5 to get one but there are some obscure situations where they put you on a static without telling you about it.

Check your Plusnet "Current Line Speed" in the Broadband tab in your member centre account. It is not a speed but an internal Plusnet profile that can restrict your speed particularly if on a Static IP. It is supposed to track the BT Wholesale IP profile which you can check on the BT Wholesale speed tester with the Additional Diagnostics tab.

Your Current Line Speed should certainly be above 70Mbps, ideally 75Mbps or over.  Mine is 80Mbps which shows it isn't tracking the BT IP profile but stuck at the maximum. It can also get stuck at lower speeds so that might be your problem.


Title: Re: Am I being capped?
Post by: sceptre on September 13, 2021, 02:42:27 PM

The link between the HG612 and the router is a 100Mbs ethernet connection so unlikely to be a problem. I assume you must be on Plusnet's Fibre Extra product to get the full 80/20 sync speeds.

Have you got a static WAN IP address, normally you pay Plusnet 5 to get one but there are some obscure situations where they put you on a static without telling you about it.

Check your Plusnet "Current Line Speed" in the Broadband tab in your member centre account. It is not a speed but an internal Plusnet profile that can restrict your speed particularly if on a Static IP. It is supposed to track the BT Wholesale IP profile which you can check on the BT Wholesale speed tester with the Additional Diagnostics tab.

Your Current Line Speed should certainly be above 70Mbps, ideally 75Mbps or over.  Mine is 80Mbps which shows it isn't tracking the BT IP profile but stuck at the maximum. It can also get stuck at lower speeds so that might be your problem.

Yes, I am on Plusnet Extra and do have a Static IP assigned.

Product: Unlimited Fibre Extra
Estimated Download Range: 71 - 72Mbps
Estimated Upload Range: 17 - 18Mbps
Minimum Guaranteed Speed: 67.3Mbps
Current Line Speed (Download): 80Mbps

Had an Openreach engineer out who did a line test from the master socket and his test equipment was indicating 79/20 - his conclusion was the HG612 might be failing for some reason, and suggested I ask plusnet for a new HomeHub5/Hub One.   I spoke with Plusnet but apparently these can't be used in Bridge mode to just use the modem portion, leaving me to use my USG and other Unifi kit.
 
Title: Re: Am I being capped?
Post by: RealAleMadrid on September 13, 2021, 03:44:12 PM
So it isn't a problem with the Plusnet "Current Line Speed" profile, but have you checked the BT IP profile? That can also cap your speed. Don't even think of getting a Hub one, it's a pretty poor rebadged BT Home Hub 5A with a Lantiq chipset and no bridge modem mode.

You could check the modem and if the USG is to blame, taking it out of the equation by using a PC configured with a PPPoE connection directly to the HG612.
Title: Re: Am I being capped?
Post by: jelv on September 13, 2021, 04:13:14 PM
but recently I'm only getting 35 down

Wired or wireless?
Title: Re: Am I being capped?
Post by: sceptre on September 13, 2021, 04:13:49 PM
So it isn't a problem with the Plusnet "Current Line Speed" profile, but have you checked the BT IP profile? That can also cap your speed. Don't even think of getting a Hub one, it's a pretty poor rebadged BT Home Hub 5A with a Lantiq chipset and no bridge modem mode.

You could check the modem and if the USG is to blame, taking it out of the equation by using a PC configured with a PPPoE connection directly to the HG612.

By checking BT IP Profile, do you mean the additional diagnostic test available on speedtest.btwholesale.com ?  If so, I've tried that with entering my landline number but I get the following message:

Quote
Summary Advanced Test
Your speed test has completed and the results are shown above, however during the test an error occurred while trying to retrieve additional details regarding your service. As a result we are unable to determine if the speed you received during the test is acceptable for your service. Please re-run the test if you require this additional information.

I'll try the direct HG612 test shortly.
Title: Re: Am I being capped?
Post by: sceptre on September 13, 2021, 04:15:22 PM
Wired or wireless?

Wired
Title: Re: Am I being capped?
Post by: sceptre on September 13, 2021, 04:36:26 PM
So, this is getting stranger!

Tried the PPoe test from my Macbook direct into the HG612 and got 70.92Mbps / 16.95Mbps - working understanding = HG612 / line are both good.
Now, onto USG troubleshooting to figure out what the heck is doing with half my bandwidth!
Title: Re: Am I being capped?
Post by: burakkucat on September 13, 2021, 05:48:46 PM
Everything looks good, so far.

Quote
Now, onto USG troubleshooting to figure out what the heck is doing with half my bandwidth!

Hmm . . . That is an odd situation. Has there been any change, whatsoever, with the USG?
Title: Re: Am I being capped?
Post by: sceptre on September 14, 2021, 04:44:36 PM
Everything looks good, so far.

Hmm . . . That is an odd situation. Has there been any change, whatsoever, with the USG?

No intentional changes :-)

After some more troubleshooting, I found some references in USG forums to do with MTU/MSS.  I tried applying an MTU of 1452 to the pppoe interface of the USG and boom! 70.93Mbps/16.92Mbps
No clue why the USG now needed a manual MTU adjustment, when it didn't previously, but I'm pleased I can get on with day-job and not spending time troubleshooting my ISP connection!

Thanks all for the help and input.
Title: Re: Am I being capped?
Post by: burakkucat on September 14, 2021, 05:40:37 PM
I tried applying an MTU of 1452 to the pppoe interface of the USG and boom! 70.93Mbps/16.92Mbps
No clue why the USG now needed a manual MTU adjustment, when it didn't previously, . . .

One of those little mysteries which come to try us! I'm pleased to know that all is now well.
Title: Re: Am I being capped?
Post by: Alex Atkin UK on September 14, 2021, 05:56:38 PM
No intentional changes :-)

After some more troubleshooting, I found some references in USG forums to do with MTU/MSS.  I tried applying an MTU of 1452 to the pppoe interface of the USG and boom! 70.93Mbps/16.92Mbps
No clue why the USG now needed a manual MTU adjustment, when it didn't previously, but I'm pleased I can get on with day-job and not spending time troubleshooting my ISP connection!

Thanks all for the help and input.


That seems a bit low, did you try 1480?

Or you could try plugging the Mac back in and check what MTU it is using?  (open a terminal and run ifconfig)
Title: Re: Am I being capped?
Post by: Weaver on September 16, 2021, 06:55:09 AM
Fragmentation, incorrect MTU might explain a lot. Is MTU 1492 any good for you? Your modem and router might not cope with MTU 1500 + 8 = 1508 (the 8 due to PPPoE overhead introduced by having a two-box setup, separate modem and router). MTU 1492 + 8 = 1500 so should be fine.
Title: Re: Am I being capped?
Post by: j0hn on September 16, 2021, 10:43:08 AM
His modem and router both support baby jumbo frames
The HG612 definitely does and the USG should also.

The current testing had confirmed the modem to be good and the issue was with the router.
Title: Re: Am I being capped?
Post by: Weaver on September 16, 2021, 11:46:27 AM
I forgot that the HG612 supports baby jumbo frames, I remember now. As you say, if the router supports PPP MTU 1508 then fragmentation is not the problem.
Title: Re: Am I being capped?
Post by: jelv on September 16, 2021, 05:03:53 PM
Rather than speculate, couldn't ping be used to find out if packets above a certain size are being fragmented?

It looks like MTU path discovery or MSS clamping (Maximum Segment Size) isn't working/supported.