My fibre speeds have NVR been S advertised for some months now,and today it's almost ground to a halt,getting 2.1 mbs on talk talks speed check this isn't good enough and been going on too long,my sister's standard broadband us faster than my fibre
Are you running speed tests on a wired or wireless device, it is best to run them on a wired device to get accurate results.
The TalkTalk staff on this community will be able to help, they will hopefully be able to respond to this post within a working day or two.
I've completed a line test now which has detected a loop fault. Does your main socket have a test socket? The sync speed looks ok. Just to confirm, are you running the speed tests wired or wireless?