Thanks for the replies so far. In general answers: I have already increased the sessions allowed per user to the maximum allowed (as stated in the OP). Looking at the resource monitor, the actual TCP sessions appears to be running between 50 and 100. This implies (to me) that it is creating but not releasing connections - and I cannot find anywhere to look and see if that is the case.
Thanks for the link to the user guide. Howver, it is running an amended firmware supplied by the ISP (Eircom), which means that the pictures do not necessarily match what I see on the screen - although many of the tables match what the router help gives. I will see if their are similarities however.
The machine is brand new, and I do not use any kind of torrent software. These symptons occured from first connection. It may be some of the bloatware, but I haven't been able to identify anything which is using netwrok resources to that degree.
Any more comments gratefully welcomed!
Regards
MD