I posted a while back about some issues I was having with my bonded ADSL from Eclipse (resold Sharedband). Throughput on each line would drop terribly, down from about 18meg peak to 3-4meg. At the time I was convinced that I had a problem with one of my BT lines - however following 3 BT engineer visits during which they were unable to see any faults on the line, even though I could show them that the throughput was nowhere near the sync speed, it has become obvious that the issue lies elsewhere.
Following the third engineer visit, Eclipse support asked me to disable all the bonding settings on the routers and run the speedtest at speedtest.btwholesale.com whilst I was experiencing a drop in throughput. To my surprise, the speedtest at BT Wholesale came back with speeds of near enough 100% of the sync speed for each line. So they sent me additional hardware - essentially an additional router for each line to do the bonding, alleviating the processing load on the netgear dg834's. For a while, no issues. 'Brilliant!' I thought, 'Problem Solved!'. Nope. It's started happening again.
So every time I notice the drop in throughput happening, I disconnect the second routers, hook my laptop into the isolated netgear on each line, and run the BT wholesale speedtest. Every time, speeds are good on the BT wholesale checker.
Which (finally!) brings me to the point in the title.
Today, I tried a different tack. When the throughput was poor, I ran the BT Wholesale speed checker on each line as usual. 11 meg on one line, 10 on the other. Then I ran speedtests at speedtest.net and speedtest.sharedband.net (which is the one eclipse reccomend to use). Even though the BT wholesale tests were 11/10meg on each line, the other two speedcheckers were showing speeds of 3/4meg.
Does this offer any pointers as to where the trouble might be? It's making me think that there's a routing issue or a router somewhere that's getting overwhelmed at certain times. Am I right in thinking that the BT Wholesale speed checker is not affecting by the ISP's routing?
Any help or insight is much appreciated, sorry for such a long post! I'm seriously at my wit's end with this, it's been going on for 7-8 months now.