Frequent Lag Spikes/Disconnects - Please Help!

[FNi]

Service: VM 50Mb
Router: Netgear WNR2000

Quick Back-story
When I first subscribed to VM 50mb just over a year ago (July 2009), I initially had a severe problem with very frequent disconnects - roughly every 15mins. After multiple phone calls to tech support I managed to persuade them that it wasn't my computer, then they sent an engineer to replace my modem which seemed to fix the problem.

Current Problem
Now about 10months later it seems like I have a less severe, but equally annoying, problem. The problem manifests in two different ways - huge lag spikes that last anywhere from 10-30 seconds and modem disconnects (3 blue lights instead of 5) which can last over an hour unless I restart the modem 3/4 times in quick succession. It has been getting progressively worse over the last 2 months.

To make matters worst, due to how random and intermittent these problems are (can be fine for a week, then really bad for a day) I've had a really hard time diagnosing the problem. I'm hoping the lag spikes are related to the connection drops so fixing one will also solve the other.

Connection Drops
This problem is very annoying but luckily only happens every few days. Suddenly the modem will drop to just 3 blue lights and there is no internet access at all. If I wait and let the modem fix itself, it can take anywhere from 30 minutes to 2 hours before internet access is restored. Alternatively if I hard restart the modem (pull out the power cord) 2 - 4 times I can usually get it to reconnect much quicker.

(Un)Luckily it happened again last Monday which was my day off so I was able to take screenshots of the modem status and event log before the problem fixed itself.

Status:
https://www.cableforum.co.uk/images/local/2010/08/41.jpg

Event Log (disconnect happened at around 2:25pm but the log is in GMT):
https://www.cableforum.co.uk/images/local/2010/08/42.jpg

Long Lag Spikes
This problem seems to mostly happen in the afternoon/evenings and has made all VOIP and online gaming virtually unusable. These spikes last anywhere between 10 and 30 seconds and stop all internet activity on every computer in the house.

To help illustrate when it's happening (and for how long) I've been using ThinkBroadband's Broadband Quality Monitor (http://www.thinkbroadband.com/ping). Their server pings your router very frequently and charts the latency. As it also reports packet loss, it has been very handy for visualising the lag spike problem.

The red patches on the following graphs indicate frequency and severity of the lag spikes.

Very Good Day (virtually no issues with lag spikes or disconnects):
https://www.cableforum.co.uk/images/local/2010/08/9.png

Average Day:
https://www.cableforum.co.uk/images/local/2010/08/10.png

Bad Day (the thick red bar is complete disconnect which fixed itself 45min later):
https://www.cableforum.co.uk/images/local/2010/08/11.png

Bad Day:
https://www.cableforum.co.uk/images/local/2010/08/12.png

Bad Day (the gap in this graph is me hopelessly trying to restart the modem so I can play an online game):
https://www.cableforum.co.uk/images/local/2010/08/13.png

I have tried (multiple times) disconnecting all machines on the network and I can assure you this is not a problem with any one computer interfering with the router or modem.

I finally got around to contacting VM phone support and they're sending an engineer tomorrow to replace the modem. However I'm worried that this won't actually solve the problem and due to the intermittent nature of the issue (and the fact that the connection is usually fine in the mornings), the VM engineer won't be able to diagnose the real fault.

Any help at all will be appreciated and if you need any further information or logs, just let me know.

Regards,
FNi.

---------- Post added at 04:31 ---------- Previous post was at 04:06 ----------

Forgot to include Upstream and Downstream:

https://www.cableforum.co.uk/images/local/2010/08/43.jpg

https://www.cableforum.co.uk/images/local/2010/08/44.jpg

[pabscars]

Your downstream power level looks way too high, and your modem logs show T3 and T4 time outs (T4's from what I can gather mean a serious issue on the network somewhere) which will explain your loss of service so I would suggest a call to tech support is in order, as an engineer will be required to get your levels in range.

When you call mention your downstream power level is too high, and they should book an engineer who will need to come and tweak your levels at the green cab up the road.

I would also call at 08:00am to ensure a UK support agent. But if you get no joy try the "thinking of leaving us" option and tell them if its not sorted you will leave. A bit drastic I know but sometimes you have to play hard ball to get problems sorted.

[FNi]

Thanks for the reply pabscars.

I'm expecting the Virgin Media engineer to arrive any time now, so is there anything else you recommend I mention to him?

The last time an engineer visited to fix a similar problem (nearly a year ago), he wasn't very helpful in the slightest and seemed quite unaware of some very basic networking terms. Hopefully I'll get better luck this time.

I'll make sure to show him the screenshots of the modem status page and the ping charts which quite clearly illustrate the frequent lag spikes.

[pabscars]

Just make sure your downstream power level has dropped before he leaves, he will probably just put a forward path attenuator on the back of your modem which should reduce the levels nearer to zero.

Then see how it goes from there but if you continue to see T3 and especially T4 timeouts then kick up a stink because according to other posts Ive read on here it means something is quite seriously wrong with your connection.

[FNi]

Well, the engineer just left.

After I explained what the problem was and showed him the logs, he replied with an honest (but disappointing) answer stating that he's very new to VM 50Mb modems and doesn't really know anything about T3 or T4 connections. I got the impression that the only thing he knew how to troubleshoot was power levels.

As you rightly guessed, he then put a 6db forward path attenuator on the back of my modem (because my downstream was "f**king high" - his words) but mentioned that he wasn't completely happy doing so because my upstream is apparently great - so any attenuator could possibly negatively effect it.

He also left a 3db attenuator here and said I should use it to replace the 6db one if it does more harm than good.

I was also given the "your internet connection looks fine so there's really nothing to fix" line and was told to continue monitoring for lag spikes and disconnects - if they continue to happen I should phone him and he'll send out someone who knows a bit more about T3 and T4...

So the question is, why on earth does Virgin Media send out engineers who don't understand their own product?

So far I haven't used anything which would flag packetloss/lagspikes (Skype, Xbox Live etc), but I have noticed that my connection speed has dropped from around 49Mb to 41Mb which is "nice"....

[pabscars]

Well at least its a start FNI, I,d be interested to see your power levels now he's fitted the attenuator, and your logs again to see if you have stopped getting the T4 time outs, don't worry about the T3's as much, as a couple a day are perfectly acceptable I believe.

I would be concerned if you were seeing dozens of T3's over the course of say an evening.

However if your still receiving poor service get on the blower again and don,t take no for an answer.

[Chrysalis]

if it helps I can post a couple of leics graphs which will make yours look outstanding. :)

from those graphs tho your problem looks like some kind of specific fault, maybe related to noise rather than congestion.