Presumably the loss of connection you're experiencing is the wireless signal between the computer(s) and the router, rather than Virgin's service itself?
Interference can cause this sort of problem and changing the Channel number with which the router broadcasts can help. With a computer connected to the router by ethernet cable, *NOT* wirelessly, open its configuration pages by typing its IP address of 192.168.2.1 into your web browser. In its Wireless settings, you should see an entry for the Channel number. The most commonly used numbers are "6" and "11", so try using one of these or, if already using one, try the other.