Here is some steps to take if you have problems with your FTTP service.
If your FTTP line is down permanently then look here for help
Is it taking a long time to load web pages, or download files? Do you have packetloss? Do you think your line should be faster than what it should be?
Information about the Openreach FTTP Optical Network Termination unit
Some of the common problems that WiFi users experience, together with measures that can be taken to mitigate them where this is possible.