Broadband 40Mbps to socket, 3 Mbps from hub: Why?

[#1]

Hoping someone out there can help with this mystery.

I was getting downloads speeds around 30 Mbps until about a month ago when the speed suddenly dropped to between 2 and 4 Mbps (depending on the time of day).

The Plusnet One Hub tells me I'm getting 40Mbps down and 9.99 upload speeds, so I thought there might be a problem with the router. Plustnet sent me a new one which I connected up today - but the problem persists. 

BTW speedcheck tells me I'm getting 3.82 this evening. The hub is connected to the master socket, and the computer is connected to the hub via ethernet cable. Wireless connection speeds to phones and iPads are similar.

Screenshots attached - Hub DSL status and BTW speedcheck stats.

Grateful for any advice on what might be going on here!

[#2]

Moderators Note

This topic has been moved from ADSL Broadband to Fibre

[#3]

Your screen shot is 2 copies of the DSL stats which, unfortunately, does not include noise margin, attenuation and errors that are more useful (see attached - but ignore Max Rate, it is "just for fun")

Phil

[#4]

Together with our network partners at Openreach we are prioritising customers who don’t have a phone line or broadband connection, meaning there might be a delay in Speed Faults being fixed. In the meantime, please raise your speed fault online at faults.plus.net