Main symptoms of throughput are Thunderbird mail client unable to connect with smtp.gmail.com to send mail mainly on big emails, websites timing out, Outlook freezing.
I ran a ping test to google.com and at the same time looked at Speedtest.net and also the Youtube test video. Everything looked great for 10 minutes or so, 5M down, 0.7M up, ping delay ranging from 35m to 100m even while streamed HD video. And virtually no packet loss (<10) showing on the Youtube video stats.
Then after 10 minutes the Youtube video froze and packet loss soared into the thousands, and test email sending failed. However, and here is the weird bit, the DSL link stayed up and the ping test hardly murmured (latency did go out to 250m but no lost pings).
Vodafone say there have not been any recent DSL resets. But the customer gets glitches several times every hour.
We tried originating and receiving phone calls on the line, and checked for filters in the right places. Nothing wrong there (but horrors, no master splitter).
In summary here is a good looking ADSL connection, which glitches occasionally from a number of different clients on the network, including 2x XP workstations, 1x iPad, and a Vodafone Sure-Signal also goes down (I think they said the phone signal level display drops away completely during a "glitch").
Given the almost continuous good test results, and the lack of DSL resets, and the continuous good ping even during a "glitch", I believe the physical network must be ok. I suggested the modem replaced, and then the DSLAM port get changed if still problematic.
Has anyone seen anything similar to this? Are there any tests which can be done to shed further light?