Forum Discussion

untruenorth's avatar
untruenorth
Joining in
2 months ago

Old chestnut: SYNC Timing Synchronization failure

I see this come up from time to time here, and a quick search suggests a number of possible causes: power levels, "area faults", for example.  The fault causes a basically unusable, but not "hard down", service: latency and packet loss go way up when trying to do anything with the connection, video calls are killed stone dead as they don't tolerate loss and retransmission, services that do tolerate retransmission/retries are slow as heck. 

The last time this issue occurred for me, for about a day or two, I was gaslit into believing that it was a fault with my equipment, as when disconnecting everything and just hooking up a laptop, the packet loss and outages went away.  As soon as I hit the connection with a speed test however, packet loss, latency, and sync failure messages abounded, putting the lie to that particular story.  (Rant: using modem mode, with your own firewall, seems to be carte blanche for VM to default to "it must be a you thing".)

And then... it magically fixed itself without me doing anything, radio silence from customer services about what that might indicate.  (We'd bailed and gone to the office to work for a few days, precluding the possibility of an engineer visit anyway).

Yesterday, the same problem has come back.  Called customer services and:

1. They can't see a fault on my modem.  But they never can, despite the logs full of sync failures, despite the downstream channels dropping out, despite the 50% uncorrectable counts against some channels.

2. They insist on sending an engineer to check the analogue side of things.  Now that's fair, but they don't show any signs of having remotely checked for anything at the head end/cab before sending someone in a van out.  (And this with the usual threat of "if it's not us, we'll charge you"). 

Now, I'm not asking for any help fixing this: I'm actually a business broadband customer (it was the only way to get 1Gig service here), so actual fixes have to go through them (or a call centre somewhere halfway around the world which doesn't seem like it's populated with people who know about networking... which is bold when business services stand a greater chance of being ordered by people who do actually know about networking).

But I'm curious to know - if anyone here knows - what checks actually take place when a fault like this is reported?

- Is the modem properly checked including logs, channels, etc?

- is the cab/upstream infrastructure checked to isolate if it's an individual customer fault, or a whole cab's worth of customers, or is the fault further upstream - before sending a man in van out?

- and is there ever a chance that VM will quit the "it's your equipment" gaslighting?

Sigh. (And don't get me started on being sold 4G backup that doesn't work in modem mode)

  • legacy1's avatar
    legacy1
    Alessandro Volta
    2 months ago

    Your a business customer so modem mode use should seem right to use and be supported its not like they can take that away many use it.

    VM hate intermittent faults their likely is a problem and even when it Docsis and logs show a problem it like “no more problem must of fixed it self” and happens on and off but there is a problem.

    you can setup a BQM to track when it happens

    Broadband Quality Monitor | thinkbroadband

    • Kath_P's avatar
      Kath_P
      Forum Team
      31 days ago

      Hi untruenorth, 

      Thanks for taking the time to contact us via the Community. It's lovely having you on board with us in the Forums. ⭐

      We're sorry to hear you're having an issue with your broadband connection. 

      I'm afraid as this is a business line, we wouldn't have any information on what checks are done by the team as we only deal with residential lines here. 

      If you have X then you can try tweeting @Vmbusinesshelp or if not you can also try these contact options here. The teams there should be able to help to provide more clarity for you.

      Thanks. 

  • untruenorth's avatar
    untruenorth
    Joining in
    27 days ago

    Update. 

    Typically, this fixed itself without intervention late last week, but I kept the scheduled engineer visit.  He was excellent, confirmed that my modem/cabling/signal/etc was all good, but recognises the hallmarks of RF interference in the local area, based all the evidence I showed him (including Samknows drops, modem stats, packet loss patterns, etc), so has requested monitoring be put in place for some of the infrastructure upstream of where I am to hopefully nail down the cause next time around. 

    This also spurred me to put in place my own monitoring to yank modem stats into Grafana so I can spot early signs of it happening again and get a case raised ASAFP.  

    The (hacked, very) scripting is based on https://github.com/hairyhenderson/hitron_coda, with stats sent to InfluxDB for Grafana to display, something like this:

     

     
    The dropoff in the bottom graph is where the modem was rebooted this morning, clearing all the counters.
     
    PS: Forum Team: the issue I suffered is in the RF domain, and will potentially have affected other customers on the same coax infrastructure, according to the engineer.  I still think it's valid asking what checks VM actually do here, as they should be the same for business and residential services.