Getting ~10% speed; lots of pre/post RS errors

[rjpieke]

For the last few years I've had my SuperHub 2 in modem mode, and it's generally been great, giving me 100% of my package speed (100mbps down; 10mbps up).

In the last week, however, that's plummeted, pretty much to exactly 10% (i.e., 10mbps down; 1mbps up).

I couldn't figure out how to get any diagnostics from it in modem mode, so I switched it back to router mode. That's suddenly unlocked my upload speed (i.e., back up to 10mbps) but the download speed is still really suffering (~25mbps).

Now that I can get diagnostics, I also note that there are a *lot* of pre/post RS errors. If I refresh the page, I can see they're seemingly being generated in the thousands per second.

Soooo ...

1 - how do we fix this?

2 - why is router mode giving me very different speeds than modem mode?

Thanks!

Here's the situation after the system's been running for ~1hr.

Modem InitialisationStage Status

Downstream Acquisition	Locked
Primary Frequency	162750000 Hz
DHCP	Done
TFTP	Done
Time Of Day	14:40:33 BST
Security	BPI+
Counters T1,T2,T3,T4,Sync,Resets	000,000,001,000,000,000

Internet ConnectionIP Address Status

WAN IP Address	82.26.68.128
Lease Time Remaining	0 days 00h:40m:13s
Expiry	Tue 5 Oct 15:20
Current Network Time	Tue 05 Oct 14:40 BST

Downstream ChannelsLock Status Channel ID Frequency Modulation Rx Power RxMER Pre RS Errors Post RS Errors

Locked	4	162750000 Hz	256 QAM	2.4 dBmV	37.4 dB	106058	763
Locked	1	138750000 Hz	256 QAM	3.0 dBmV	30.5 dB	2943285	2631850
Locked	2	146750000 Hz	256 QAM	3.5 dBmV	35.2 dB	2756548	77915
Locked	3	154750000 Hz	256 QAM	3.3 dBmV	37.6 dB	274871	300
Locked	5	170750000 Hz	256 QAM	2.5 dBmV	37.1 dB	289397	355
Locked	6	178750000 Hz	256 QAM	3.0 dBmV	37.9 dB	325040	1096
Locked	7	186750000 Hz	256 QAM	2.4 dBmV	37.4 dB	376329	437
Locked	8	194750000 Hz	256 QAM	1.7 dBmV	37.6 dB	153697	1453

To reset the Pre and Post RS error counts please use the Downstream screen under the router status screen available from the login page.

Upstream ChannelsLock Status Channel ID Frequency Modulation Tx Power Mode Channel Bandwidth Symbol Rate

Locked	10	32600000 Hz	ATDMA	47.5 dBmV	64QAM	6400000 Hz	5120 Ksym/sec
Locked	12	25800000 Hz	ATDMA	47.5 dBmV	64QAM	6400000 Hz	5120 Ksym/sec
Locked	8	46200000 Hz	ATDMA	49.3 dBmV	64QAM	6400000 Hz	5120 Ksym/sec
Locked	9	39400000 Hz	ATDMA	47.8 dBmV	64QAM	6400000 Hz	5120 Ksym/sec

[jbrennand]

Looks like you have a noise ingress issue on down channel 1. Can you start from a blank page and try this....
________________________

Switch the Hub off and unplug it from the mains supply for five minutes. Whilst it's off, do a quick check that all of your coax cable connections are in nice and "finger" tight - at the Hub and wall box and also at any connectors etc. Ensure there are no “unterminated cable loose ends. Disconnect all the connections and reconnect to be sure. Also check that the internal wiring is ok with no kinking or chaffing, check that all looks good with the outside cabling and wall box (no “staples, etc.,) piercing the cables.. Then switch the Hub back on and leave ~5 minutes

When all done, check back in the settings and ensure that the RS error counts and T3 errors have all reset to 0. Then check every hour or so to see if they start accumulating quickly - they shouldn't. A few are normal on a SH2 (mine are often around ~100 - but If they do accumulate rapidly (particularly the postRS ones) you have a problem (noise) that only a Tech visit will sort.

Also the SNR on channel 1 is only 30.5 dB - thats far too low - should be above 34 like the other 7 channels - it signifies noice is overwhelming signal - if that is still low you will need a Tech visit

[rjpieke]

Thanks John! I traced the cable from the modem to the street. No obvious kinks or damage. I disconnected and reconnected all the connections, and restarted.

The SNR for all downstream channels is now between 37.5 and 38.5, but I still accumulated several million RS errors overnight (both pre and post), and speedtest is still only reporting ~30-40mbps (instead of 100-110mbps in the past).

Historically when I've had slow connection days, they've mysteriously vanished on their own, but this one is more persistent. What's the path to a tech visit? The last time I tried calling the customer support line, it was a long and not very fruitful process.

[jbrennand]

I will flag for VM to come and comment. In the meantime, can you try these things
__________________

Check first for “known network faults”

As well as trying the “check service,” Area status webpage" (link at top right of this forum), also try the “free & automated” Service Status number - 0800 561 0061 - which usually gives the most up to date info. and tells you of more local issues down to postcode level.
_________________________________________________________

Then, if you haven’t already, set up a free, secure and “offlsite” - “Broadband Quality Monitor” to continually monitor the state of your connection and record any true network dropouts , latency issues, packet drops, etc - it will thus allow you to differentiate between those and simple wifi dropouts. It does it 24/7/365 and it keeps a visual record of any/all of your network disconnections, useful data to have to match to the Network logs (in your Hub settings) and also in discussions with VM - note it will take a few hours to start seeing a sensible picture - post up the “link” to the “share live graph” (as per instructions on the TB website) when it starts to develop.

https://www.thinkbroadband.com/broadband/monitoring/quality
___________________________________________________

[rjpieke]

Thanks John. I tried to set up a BQM yesterday but it just shows 100% packet loss. Is there something on the SH2 I need to modify? I've (just now) tried turning off the firewall.

[jbrennand]

(Google for your i.p address. Then check in the BQM settings that you have the i.p. address inputted correctly - because you will get different i.p. addresses in modem and router mode. Plus - VM do change them occassionly (mine changed recently for the first time in years).

If in modem mode the the setting will be in your own router's settings - "allow ICMP requests" or similar. Although I have an SH2 - I dont actually know if/where that setting is as it has never run in router mode 🙂

[rjpieke]

Ah, thanks. Buried in the Advanced settings there's a "Ping" page with:

WAN Ping Respond

    Respond to ICMP echo requests sent to WAN IP  

I've now turned that on.

[Akua_A]

Hi @rjpieke,

Welcome back to our community forums and thank you for your first posts. 

Sorry to hear you are having issues with RS errors. I can understand this is not ideal and want to best help. I have had a look back end into your account and connection and I am unable to see anything that may have caused this. 

I am however glad to see @jbrennand has been assisting you regarding this. Since making the changes are you still getting these errors?

Please get back to us when you can.

Thanks,

[rjpieke]

Hi Akua_A ... yes, the situation remains.

[Akua_A]

In this case, I have sent a private message to further look into this for you.

Please look out for the purple envelope and provide a response when you can.

Thanks,