It is quite normal to experience a periodic (up to once every 12 hours) loss of connection on standard domestic services; usually immediate reconnection is automatically made and often the break is not noticed. This loss is more frequent If you have just started using broadband, or just migrated from a previous ISP, so you should be aware that this is most likely to be noticeable for the first couple of weeks of service and does not indicate a fault.  The reason is that your ISP's wholesale provider will probably be using rate adaptive technology to maximise the reliable speed at which service can be delivered to you. 

When you send or receive data over the Internet (web pages, file downloads, e-mail etc.) it is broken up into packets, each of which is transmitted separately - possibly over differing routes.  If the sending computer does not receive an acknowledgement that a packet has been successfully received, then that packet is automatically retransmitted.  The number of these dropped and retransmitted packets should be as low as possible to avoid transmitting the same data more than once.  A count is made of such packet drops and if the ratio of total sent to total dropped is too bad, your broadband signal is automatically dropped and then re-enabled at a slower speed.  If, however, there are very few packet drops, then your broadband signal is automatically dropped and then re-enabled at a higher speed. 

This adaption of the speed to maximise your reliable use happens constantly, but it is much more noticeable for the first week or two as it happens more frequently initially.  If you connect to the Internet through a reasonable quality router the connection should be remade automatically and you may not notice that it has happened.  Cheaper routers are not as good at retrying to make a connection once it is dropped.

To speed up the remaking of a dropped connection, or if your modem/router does not automatically re-make the connection, simply remove the power from the router/modem, wait 10 seconds (to allow the capacitors to drain) then reapply the power.  This is known as power cycling.  Most routers take between one and two minutes to initialise, and after that you should have a connection. 

What affects quality of service ?

In order of significance.

• The distance between your modem/router and the BT exchange.  House wiring can extend this length and the BT wires probably take a circuitous route between the exchange and your property.  As a very rough guide, if you are less than 20 metres from the exchange you may get 7½ Mbps and that reduces to next to nothing as you reach 6 km from the exchange.

• The quality of cabling.  If BT use modern thick gauge copper cabling with no weak joints where water has ingressed,  you will get the best signal up to your master socket.  If you have your modem/router plugged into an extension socket, or worse, use a portable phone extension cable, the signal strength will suffer.  Old phone leads contain a high proportion of aluminium - fine for voice calls but they are lousy for broadband as they enable a degree of crosstalk.  DIY phone wiring in the house is often sub-standard.

• Contention ratios.  Almost all residential broadband is shared with other people in your neighbourhood.  At the BT exchange you may be multiplexed with up to 50 others all vying for a share of the available bandwidth.  Also the ISP servers will allocate between 20 and 50 users to a line.  The consequence is that you will get faster speeds if you use your connection at uncommon times of the day.

• Electromagnetic interference will degrade your signal.  Try to keep the signal wires away from power cables, wireless phones, speakers and other such distortionary devices.

• Modem/router quality.  Sure you can buy them cheap, but you get the quality you pay for generally.

There is an excellent 17 page leaflet 'Broadband Max - Myths and Legends' produced by BT Wholesale.