Why does my broadband connection sometimes appear intermittent, usually accompanied by a flashing light on my router?
This is most likely to be the broadband service automatically adjusting your speed in order to maintain the fastest possible stable connection (a process known as re-synching). Re-synchs are usually triggered by electrical interference affecting your phone line. The re-synch process requires the broadband signal to be dropped for 20-60 seconds while a new stable speed is identified. If you have a router or hub, your broadband service should then re-connect automatically.
