I have the same problem. From time to time I lose my broadband connection. Rapid flashing yellow light on BT Home Hub 2.0. Engineers cannot find any faults. The only way to get the broadband back up is to make or receive a voice phone call. When a call comes in the light immediately goes to solid yellow and shortly after that to blue. Then the broadband works perfectly again – until next time!
Did you discover the cause of the similar fault you looked at?