had the engineer out again today. he did some test but still no luck. still the same lag spikes. he `s never seen anything like it and hes going to show open reach this forum post and try and get something done.
Same for me, this was the first time I had an engineer visit, he tested the line, no faults, which I already knew based on the router statistics. He didn't have any idea of what to try to change, he tried everything he knew, basically drew a blank. He did say that the problem was beyond the level that he operates, his remit is to find and solve line faults, since there was no fault with the line there was nothing he could do and also affirmed that the engineers that might be able to solve this aren't available to the public.
At least now I can argue there is no fault and it's pointless to keep sending engineers out to test the line...
Having just moved over to BT I can see the spike when using their kit.
However I like to use my own kit, I had this same kit in when I moved over, the same user name from previous ISP in my own set up, this issue does not occur!
What does occur and I would expect any other service using the connection increases my latency on both setups. Although spike not occuring in my own setup, just expected steady increase.