Dear Ian,
Thanks for your email.
The slow speed is caused during the evening hour/peak hours since the number of browsers increases; this is linked to “Contention Ratio”
To provide a cost effective service - our ADSL services are 'contended' (shared) at the following ratios:
50:1 ADSL 500, 1000 & 2000 Solo
20:1 ADSL 500, 1000 & 2000 Business
This contention is applied within the BT network - both locally with other users on your telephone exchange and within the BT network as it connects into our network.
What this means in the 'worst case' is that you could be sharing a 500 Kbit/s connection with up to 49 other users. So if they were all using it at the same time 'theoretically' you would only get 10 Kbit/s (not very fast at all - in fact quite a bit slower than a normal modem).
However, 'in reality' this scenario is very unlikely to happen and you should usually find it to be far faster than a modem connection.
ADSL relies on individual users not making unreasonable traffic demands on the network to provide fast access speeds for all - please see here for further details.
Remember if you are not getting the speed you expect it can be due to the contention ratio but also too many other factors including the capacity of the remote site you are accessing.
If you have any further queries you can chat online with one of our agents, to chat online please click on the link below, and enter your Virgin Media email address and password to access our online chat agents.