Could you point me in the direction of what you read to see there is a fault? guessing something to do with the SNR margin the draytek displays? this morning i plugged the router into my sky line, just to see the difference. it is attached below.
The speed on your second line is much lower than the handback threshold stated on the DSLChecker. This could indicate a line problem, poor Openreach records or poor internal wiring. You confirmed that there is no extension wiring thus ruling that out and its unlikely to be poor OR records especially as you have another line performing much better from the same cabinet.
You have a Huawei FTTC DSLAM. These initially target a SNR of 6 both upstream and downstream to ensure a stable connection (the downstream SNR might then reduce to as low as 3 as is the case with your Sky line)
The maximum attainable speeds estimated by your modem on the 2nd line are close to your sync speed and showing a SNR of 6 - hence showing its doing as much as it can given the current line. If DLM had artificially reduced your sync speed to ensure a stable connection than your SNR figures would be higher - this is not the case - hence not thinking a DLM reset would help.
As such, its likely to be a wiring issue/line fault of some kind - especially as its a new installation. It could be you're just unlucky re: the quality of the new line but the fact its maximum sync speed is far below OR's expectations gives you leverage to get the ISP to get an engineer to investigate.