This is not a broadband speed problem but I am not sure, at this stage, what it actually is so I won't move this post again.
From your description I assume that the power light on the router remained on when the other lights went out.
I don't understand what would cause the wireless light to go out as that should be independent of the state of the internet connection.
A few questions.
When this happens can you contact the router via a wired connection or doesn't that work either.
When you say constantly knocking off would it be correct to say that you are getting constant or frequent disconnects from the internet
Have you tried using the test socket behind the master socket as per this picture
When the router is connected what are the stats attenuation, noise margin and speeds.
What does this link say https://portal.plus.net/my.html?action=data_transfer_speed