Menu
Reply
ndneal
  • 3
  • 0
  • 0
Joining in
98 Views
Message 1 of 4
Flag for a moderator

Slow internet, connection aborts, T3 timeouts

Hi all,

 

I’ve been trying to get to the bottom of a fairly subtle network issue we’ve been seeing recently. We’ll likely have to book an engineer, but I wouldn’t mind understanding what the problem could be. Any input would be greatly appreciated.

 

Basically the LAN clients are seeing frequent TCP drops and handshake timeouts. So video streaming generally works okish, but going on the web is a pain, so is VPN and video conferencing, which makes wfh difficult.

 

The setup is a Hub 3 in modem mode with an Asus router. The router is not the problem, same issue when the Asus if off and the Hub 3 is in router mode instead.

 

Looking at the downstream:

 

Power levels: lowest is 9.3dB, highest is 14.1. That is too high surely? SNR is 38 for most channels, 40 for some. That seems ok? RxMER is 38.9 … 40.1 for all channels. Very few pre RS errors and not going up, post RS error count stable at zero for all channels.

 

Upstream: posting as image:

 

upstream.png

 

Looking at the log, there are regular (frequent?) T3 timeouts, about 10/hr and always on the same channel. Also I have seen some channels drop down to 16QAM. Seems the upstream is limping?

 

The coax from the VM outlet to the Hub is squeezed into the conduit rather tightly, so I thought there might be some kinks in there causing issues. However the problem only started recently, the same installation worked fine before. I also tested with a free coax cable instead and that didn’t really make any difference.

 

Connection is directly from the wall socket to the hub, no splitters or attenuators, just a galvanic isolator in between.

 

Many thanks,

ndneal

0 Kudos
Reply
Tudor
  • 7.96K
  • 639
  • 1.38K
Alessandro Volta
93 Views
Message 2 of 4
Flag for a moderator

Re: Slow internet, connection aborts, T3 timeouts

10 is the max downstream power level, so at least one is out of spec. Please post full up/downstream and network stats. You will need a technician’s visit to rectify, either phone customer services or wait a few days for a VM staff member to get to your post.


Tudor
There are 10 types of people: those who understand binary and those who don't and F people out of 10 who do not understand hexadecimal c1a2a285948293859940d9a49385a2
0 Kudos
Reply
ndneal
  • 3
  • 0
  • 0
Joining in
71 Views
Message 3 of 4
Flag for a moderator

Re: Slow internet, connection aborts, T3 timeouts

Thanks,

ah yes its 10db for VM. In that case they're virtually all out of spec.

Downstream bonded channels

Channel Frequency (Hz) Power (dBmV) SNR (dB) Modulation Channel ID

14027500009.638256 qam30
220275000013.538256 qam9
321075000013.538256 qam10
421875000012.938256 qam11
522675000012.838256 qam12
623475000012.438256 qam13
724275000012.338256 qam14
825075000011.938256 qam15
925875000011.938256 qam16
1026675000011.438256 qam17
1127475000011.338256 qam18
122827500001138256 qam19
132907500001138256 qam20
142987500001138256 qam21
1530675000010.838256 qam22
1631475000010.838256 qam23
1732275000010.938256 qam24
1833075000011.138256 qam25
1937075000010.638256 qam26
2037875000010.838256 qam27
213867500001038256 qam28
223947500001038256 qam29
234107500009.538256 qam31
244187500008.838256 qam32



Downstream bonded channels

Channel Locked Status RxMER (dB) Pre RS Errors Post RS Errors

1Locked38.650
2Locked38.950
3Locked38.650
4Locked38.950
5Locked38.950
6Locked38.900
7Locked38.900
8Locked38.600
9Locked38.600
10Locked38.600
11Locked38.950
12Locked38.960
13Locked38.9110
14Locked38.650
15Locked38.650
16Locked38.900
17Locked38.950
18Locked38.600
19Locked38.600
20Locked38.950
21Locked38.900
22Locked38.660
23Locked38.650
24Locked38.600

 

Upstream bonded channels

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

14619999338.3512064 qam11
23260000034.8512064 qam13
33940000036.3512064 qam12
45369999640.8512064 qam10



Upstream bonded channels

Channel Channel Type T1 Timeouts T2 Timeouts T3 Timeouts T4 Timeouts

1ATDMA0000
2ATDMA0030
3ATDMA0000
4ATDMA0000

 

(just rebooted the modem so T3 timeout count is low)

Any ideas why this can happen all of a sudden (since Wed or thereabouts)? Did we get moved to another tap?

Downstream rates are quite near the line max whereas upstream bps is abysmal.

 

Cheers

ndneal

0 Kudos
Reply
ndneal
  • 3
  • 0
  • 0
Joining in
41 Views
Message 4 of 4
Flag for a moderator

Re: Slow internet, connection aborts, T3 timeouts

Solved. For now.

Set up a BQM monitor which showed massive packet loss to the router until about 8pm yesterday, at which point the problem magically disappeared. Clearly a VM network problem upstream. The massive T3 timeouts have gone now. Nothing to do with the downstream power levels, these are completely unchanged.

VM are hilarious. Had an engineer booked, booking was cancelled. Finally got through to someone on the phone (!) after about an hour in the loop, had them schedule a new booking for today, only to have that silently cancelled - no engineer showing up, no phonecall, no text no mail. Great.

VM customer service truly is ... unique. Not in a good way. Luckily our contract is running out soon and will most decidedly not be extended. Fingers crossed there will be no more outages like that until then.

0 Kudos
Reply