Both the ptn and ptw bng's for me seem ok, as for the other 3 pcl's bngs i can't say about throughput as i did not stay connected to them, as the base latency on them wasn't as low as it should be, It's possible that the end points or some of their end points are the reason behind the low throughput, but these are not visible to us,
This would explain why a certain gateway doesn't give poor performance to everyone connected to it or at least go some way to explaining
I remember last year there being several announcements regarding them adding more capacity for data transit but nothing this year about it that i can recall, which may indicate that they have stopped increasing bandwidth, but continued taking new customers ? Looking at the thread on the plusnet forum, that 23:30pm time is all too familiar to me , last year i had similar issues with poor throughput during peak times but mainly Sunday & Mondays , but did occur other days if not the sun or Mon, Apparently there was no congestion back then either, even though the tbbqm showed the peak latency hump some of the time throughput was impacted
Is your upstream throughput also impacted when uploading using FTP in particular, mine was, although difficult to pin point if it was the remote FTP server or plusnet, throughput would be reduced, and the number of active threads would be limited to 2 or 4
