Your stats suggest you have had internet connection for about 1.5days but your noise margin is exceptionally high causing low connection speed
was this a self install? If so have you tried connecting to the test socket with a new filter
You could try a hub reset using the recessed button on back and hold till lights flash
although I understand you have a SSFP they do go faulty and you could check by using the test socket with a filter and see if that helps your conenction
if neither help your connection and noise margin still 30db+ then you need to phone customer services and get engineer visit
Looks like a faulty SSFP request an engineer to solve it as it is BT's equipment that is faulty. You won't be charged for it.
I think its just co-incidence that it worked at the test socket, as the stats are the same from the SSFP front socket, so its not faulty.
You need to do all tests using an Ethernet connection, just in case its your wireless thats intermittent. It looks to me like a problem with your computer, so I would be reluctant to arrange a visit, as you are likely to be charged.
There are intermittent DNS problems being reported on Infinity, which would cause pages to fail. Testing using an Ethernet connection would show if that is the issue.
The OP has posted line stats with a very high noise margin, so there's obviously a noise problem not a PC problem, the OP needs an engineer visit to solve the noise problem.