Although unlikely, it’s always best to eliminate any potential internal issues, that why its required to test at the master socket test port ( this eliminates any internal wiring issues ) , if there is only one socket in the house and that’s the master then perhaps it’s less important, but I know of an instance where someone used an extension socket for their broadband, they were of the opinion that as it was previously OK and nothing had changed , it cannot be ‘internal’ , however the extension cable had been run under a carpet across a door threshold, and years of people effectively walking on this cable had resulted in the fault , for the few seconds needed to expose the test port and plug the phone/router in there I would suggest is worthwhile.
Someone may be along to indicate how to get to the advanced settings ....your current performance is well below what even an ‘impacted’ line to your address is predicted to deliver , so it’s clear there is an issue, however if you have previously had engineer visits you would hope that any ‘internal’ issues have already been eliminated.
BT don’t lower your speed, the FTTC system employs dynamic line management, basically if the line has ‘issues’ it lowers the speed for the sake of stability....unfortunately sometimes , if the fault is cleared it can take a while before the line speed is restored to previous levels, if the fault is still present then obviously the speed you are currently getting will remain until the fault is cleared...hence the ‘need’ to check for noise....if the noise is intermittent ( only when it’s raining for example ) quite often you need to keep reporting it, as the engineer on the initial visits may be inclined to say it was OK when they checked and that could be because it wasn’t raining at the time
