Mornin' all. After a few months of iffy health, I am back in the fray. Thanks to all who gave their time and thoughts to help me resolve the line problems that I had put up with for over three years since MaxADSL arrived.
Eventually, replacement of a faulty filtered faceplate seemed to effect the crucial improvement. It was a pyrrhic victory. Although disconnects are now unknown and I see a synch speed of 5240kbps, the networks my traffic passes through are seemingly constipated. I am guessing that router congestion is a very real issue at certain times. There may also be an issue with contention on the other side of the telephone exchange. Web sites no doubt suffer from constipation with servers struggling against lengthening queues as demand outstrips supply.
At times, the real downstream speed reaches 4000kbps but it can be as low as 2000kbps at certain times on certain days (using
www.speedtester.bt.com). I enquired at PlusNet, my ISP about this and received advice that I should connect through the test socket
. Clearly, whoever answered my enquiry had either not understood it or had not read it properly.
I have done what I can to optimise my TCP/IP settings. MTU is 1430, RWIN is 111200, window scaling, time stamping, selective acks, path MTU discovery and black hole detection are all enabled, max duplicate acks is 2, TTL is 128, my router's MTU is also 1430 and it is permitted to respond to pings.
There must be something I am failing to take account of but I cannot help thinking that the UK internet infrastructure is analogous to our congested motorway network and congested motorway junctions are analogous to congested routers.