Loss of Sync. & Connection problems

[Mark S]

I have been having many problems with my 20Mb XL connection for the past three to four weeks. It sometimes takes 2-3 reboots of the modem (Ambit 256) to get a connection as the Ready light keeps flashing constantly. My modem log is also showing frequent loss of sync. Quite frequently at peak times I get poor download speeds (2-4MB). I know a couple of other people in the Colchester area having the same problem so I doubt it is the modem.

Another problem is that my PC's network card loses the internet connection completely and I have to diasble and re-enable the LAN connection, a yellow warning triangle appear over the network icon.

Sun Dec 27 19:40:50 2009 Sun Dec 27 19:40:50 2009 Critical (3) Started Unicast Maintenance Ranging - No Response received - ...
Sun Dec 27 18:39:34 2009 Sun Dec 27 18:39:34 2009 Information (7) Downstream sync ok
Sun Dec 27 18:39:34 2009 Sun Dec 27 18:39:34 2009 Information (7) locked and synced to rescue CMTS...all is well!
Sun Dec 27 18:39:34 2009 Sun Dec 27 18:39:34 2009 Information (7) Downstream sync ok
Sun Dec 27 18:39:34 2009 Sun Dec 27 18:39:34 2009 Critical (3) SYNC Timing Synchronization failure - Loss of Sync
Sun Dec 27 18:39:34 2009 Sun Dec 27 18:39:34 2009 Information (7) Downstream sync failed
Sun Dec 27 18:39:34 2009 Sun Dec 27 18:39:34 2009 Information (7) Downstream sync ok
Sun Dec 27 18:39:33 2009 Sun Dec 27 18:39:33 2009 Information (7) locked and synced to rescue CMTS...all is well!
Sun Dec 27 18:39:33 2009 Sun Dec 27 18:39:33 2009 Information (7) Downstream sync ok
Sun Dec 27 18:39:32 2009 Sun Dec 27 18:39:32 2009 Critical (3) SYNC Timing Synchronization failure - Loss of Sync
Sun Dec 27 18:39:32 2009 Sun Dec 27 18:39:32 2009 Information (7) Downstream sync failed
Sun Dec 27 16:49:57 2009 Sun Dec 27 16:49:57 2009 Information (7) Downstream sync ok
Sun Dec 27 16:49:57 2009 Sun Dec 27 16:49:57 2009 Information (7) locked and synced to rescue CMTS...all is well!
Sun Dec 27 16:49:57 2009 Sun Dec 27 16:49:57 2009 Information (7) Downstream sync ok
Sun Dec 27 16:49:57 2009 Sun Dec 27 16:49:57 2009 Critical (3) SYNC Timing Synchronization failure - Loss of Sync
Sun Dec 27 16:49:57 2009 Sun Dec 27 16:49:57 2009 Information (7) Downstream sync failed
Sun Dec 27 16:49:57 2009 Sun Dec 27 16:49:57 2009 Information (7) Downstream sync ok
Sun Dec 27 16:49:57 2009 Sun Dec 27 16:49:57 2009 Information (7) locked and synced to rescue CMTS...all is well!
Sun Dec 27 16:49:57 2009 Sun Dec 27 16:49:57 2009 Information (7) Downstream sync ok
Sun Dec 27 16:49:56 2009 Sun Dec 27 16:49:56 2009 Critical (3) SYNC Timing Synchronization failure - Loss of Sync
Sun Dec 27 16:49:56 2009 Sun Dec 27 16:49:56 2009 Information (7) Downstream sync failed
Sun Dec 27 16:48:14 2009 Sun Dec 27 16:48:14 2009 Information (7) Downstream sync ok
Sun Dec 27 16:48:14 2009 Sun Dec 27 16:48:14 2009 Information (7) locked and synced to rescue CMTS...all is well!
Sun Dec 27 16:48:14 2009 Sun Dec 27 16:48:14 2009 Information (7) Downstream sync ok
Sun Dec 27 16:48:14 2009 Sun Dec 27 16:48:14 2009 Critical (3) SYNC Timing Synchronization failure - Loss of Sync
Sun Dec 27 16:48:14 2009 Sun Dec 27 16:48:14 2009 Information (7) Downstream sync failed
Sun Dec 27 16:48:14 2009 Sun Dec 27 16:48:14 2009 Information (7) Downstream sync ok
Sun Dec 27 16:48:14 2009 Sun Dec 27 16:48:14 2009 Information (7) locked and synced to rescue CMTS...all is well!
Sun Dec 27 16:48:14 2009 Sun Dec 27 16:48:14 2009 Information (7) Downstream sync ok
Sun Dec 27 16:48:13 2009 Sun Dec 27 16:48:13 2009 Critical (3) SYNC Timing Synchronization failure - Loss of Sync
Sun Dec 27 16:48:13 2009 Sun Dec 27 16:48:13 2009 Information (7) Downstream sync failed
Sun Dec 27 16:44:54 2009 Sun Dec 27 16:44:54 2009 Information (7) Downstream sync ok

My router stats are :-

Cable Modem Downstream
Downstream Lock : Locked
Downstream Channel Id : 47
Downstream Frequency : 315000000 Hz
Downstream Modulation : QAM256
Downstream Symbol Rate : 6952 Ksym/sec
Downstream Interleave Depth : taps12Increment17
Downstream Receive Power Level : 2.7 dBmV
Downstream SNR : 38.4 dB

Cable Modem Upstream
Upstream Lock : Locked
Upstream Channel ID : 1
Upstream Frequency : 47400000 Hz
Upstream Modulation : QAM16
Upstream Symbol Rate : 2560 Ksym/sec
Upstream transmit Power Level : 48.8 dBmV
Upstream Mini-Slot Size : 2

I would be most grateful of any suggestions.

Thanks, Mark.

[Peter_]

Your power levels are fine but the may be a local issue on the network causing your problem so a call to Tech support may be in order.

You need to call Tech Support which is open 24/7 on 151 from your Virgin Media Phone.

It's absolutely free.

Or call 0845 454 1111 from any other phone line.

[Sephiroth]

Your modem stats look fine and do not bear out what I'm going to suggest. But it needs doing in case you have an instantaneous value that isn't the case when you lose sync.

If there is nothing wrong at the VM end (and I'm not saying there isn't) then:

1/
Take your modem stats and note them. Look inside your internal wall box. Anything adrift there? Do you have more splitter points than you have cables connected (tightly)? If so, then you could go to Maplin (I hope) and buy a terminator to close off an RF interference point. Anyway, before considering terminators, do a bit of cable wiggling and take the stats again.

2/
Take your modem stats. Look outside at your external wall box. See if there's any water/ice ingress. Look for discoloured metal. You would have problems if this were so. Do a bit of wiggling and see if the modem stats change. If they do, the engineer will have do do something non-trivial to rectify the situation. When you put that back together, make sure there's a good seal to external ingress.

This wiggling is to disturb whatever di-electric conditions pertain. It night have no effect - but you know how that sort of trick works.

3/
if there is any possibility that your coax cable is pinched get it replaced with a suitable length of RG6 cable, nicely fitted so that there is no possibility of RF pickup/interference.

4/
Think about what may have changed in your modem room. Is there noisy electrical equipment that you can associate with your problems?

5/
Think about your ethernet cable. Is it Cat 5e at least and is there any possibility of it picking up or inducing unwanted RF?

Loss of Sync is usually an RF problem in my experience and could,of course, be at the VM end.

I hope this helps.

[Mark S]

Thank you Seph for the info I will look at everyone of these points later on and post my findings. :)

I don't know if its coincidence but there was an outage which affected the Ipswich, Felixstowe and Colchester area about a month ago thats when my problem started.

[Sephiroth]

The rain, flood, snow & tempest did a lot of damage to street boxes, wall boxes & so on.

Also a month or so ago, VM started messing around in a ham-fisted manner (IMO) with their network to solve a variety of unrelated problems, so far as I can piece together. Whether or not this took place in your area I don't know. It appears that they put half their Glasgow & Manchester users on the other half's UBRs while they did something to the out of service half. In the middle of this, the Motorola BSRs started re-booting and the displaced 10 Mbps users felt the additional wrath of that issue. Brighton had much the same, Swansea, I believe and so on.

In the middle of all this, rain, snow, dead dogs - you name it.

And here I am suggesting you look at the wall box in your garden! As if the cat hadn't shat itself already!

[Mark S]

I have checked everything that you mentioned, the outside wall box was dry inside and full of dead insects and spider webs that I removed. The wiring in the box is messy but all looks ok. All my ethernet cables are good quality ones rated for up to 1Gb/s. I have no other electrical equipment turned on apart from my PC.

I have wriggled most of the cables and the disconnections still persist. I cannot see any thing else obvious that is causing any problems.

Mon Dec 28 15:44:32 2009 Mon Dec 28 15:44:32 2009 Information (7) Downstream sync ok
Mon Dec 28 15:44:32 2009 Mon Dec 28 15:44:32 2009 Information (7) locked and synced to rescue CMTS...all is well!
Mon Dec 28 15:44:32 2009 Mon Dec 28 15:44:32 2009 Information (7) Downstream sync ok
Mon Dec 28 15:44:31 2009 Mon Dec 28 15:44:31 2009 Critical (3) SYNC Timing Synchronization failure - Loss of Sync
Mon Dec 28 15:44:31 2009 Mon Dec 28 15:44:31 2009 Information (7) Downstream sync failed
Mon Dec 28 15:37:19 2009 Mon Dec 28 15:37:19 2009 Information (7) Downstream sync ok
Mon Dec 28 15:37:19 2009 Mon Dec 28 15:37:19 2009 Information (7) locked and synced to rescue CMTS...all is well!
Mon Dec 28 15:37:19 2009 Mon Dec 28 15:37:19 2009 Information (7) Downstream sync ok
Mon Dec 28 15:37:19 2009 Mon Dec 28 15:37:19 2009 Critical (3) SYNC Timing Synchronization failure - Loss of Sync
Mon Dec 28 15:37:19 2009 Mon Dec 28 15:37:19 2009 Information (7) Downstream sync failed
Mon Dec 28 15:37:19 2009 Mon Dec 28 15:37:19 2009 Information (7) Downstream sync ok
Mon Dec 28 15:37:19 2009 Mon Dec 28 15:37:19 2009 Information (7) locked and synced to rescue CMTS...all is well!
Mon Dec 28 15:37:19 2009 Mon Dec 28 15:37:19 2009 Information (7) Downstream sync ok
Mon Dec 28 15:37:18 2009 Mon Dec 28 15:37:18 2009 Critical (3) SYNC Timing Synchronization failure - Loss of Sync
Mon Dec 28 15:37:18 2009 Mon Dec 28 15:37:18 2009 Information (7) Downstream sync failed
Mon Dec 28 15:37:17 2009 Mon Dec 28 15:37:17 2009 Information (7) Downstream sync ok
Mon Dec 28 15:37:17 2009 Mon Dec 28 15:37:17 2009 Information (7) locked and synced to rescue CMTS...all is well!
Mon Dec 28 15:37:17 2009 Mon Dec 28 15:37:17 2009 Information (7) Downstream sync ok
Mon Dec 28 15:37:17 2009 Mon Dec 28 15:37:17 2009 Critical (3) SYNC Timing Synchronization failure - Loss of Sync
Mon Dec 28 15:37:17 2009 Mon Dec 28 15:37:17 2009 Information (7) Downstream sync failed
Mon Dec 28 12:40:24 2009 Mon Dec 28 12:40:24 2009 Information (7) Downstream sync ok
Mon Dec 28 12:40:24 2009 Mon Dec 28 12:40:24 2009 Information (7) locked and synced to rescue CMTS...all is well!
Mon Dec 28 12:40:24 2009 Mon Dec 28 12:40:24 2009 Information (7) Downstream sync ok
Mon Dec 28 12:40:24 2009 Mon Dec 28 12:40:24 2009 Critical (3) SYNC Timing Synchronization failure - Loss of Sync
Mon Dec 28 12:40:24 2009 Mon Dec 28 12:40:24 2009 Information (7) Downstream sync failed
Mon Dec 28 12:35:34 2009 Mon Dec 28 12:35:34 2009 Information (7) Downstream sync ok
Mon Dec 28 12:35:34 2009 Mon Dec 28 12:35:34 2009 Information (7) locked and synced to rescue CMTS...all is well!
Mon Dec 28 12:35:34 2009 Mon Dec 28 12:35:34 2009 Information (7) Downstream sync ok
Mon Dec 28 12:35:34 2009 Mon Dec 28 12:35:34 2009 Critical (3) SYNC Timing Synchronization failure - Loss of Sync
Mon Dec 28 12:35:34 2009 Mon Dec 28 12:35:34 2009 Information (7) Downstream sync failed
Mon Dec 28 12:35:34 2009 Mon Dec 28 12:35:34 2009 Information (7) Downstream sync ok
Mon Dec 28 12:35:34 2009 Mon Dec 28 12:35:34 2009 Information (7) locked and synced to rescue CMTS...all is well!

Thanks Seth. for taking the time to reply to my post :)

I had this issue before with my old BT ADSL broadband thats why I went with cable and was never expecting it to happen again. I will have to try to contact the UK call centre as I never seem to get anywhere with the Indian one.

[III]

Call at 8 am Mark, you'll have more chance of getting a UK agent.