I had this firmware update too SG4B1000E020 on 23/11/2020!!!
Noticing lower speeds and sometimes it gets so bad I get crazy ping +200ms online games. Also when someone uses Messenger video call the broadband speed can't take it and everything lags. When there is no Alexa music playing or video calls being made, it is fine most the time. Put in a fault ticket and a complaint ticket but both have had no responses from BT!!!.
I should easily get 34Mbps and 7Mbps. Can watch Netflix at 4k, be on a video call on Messenger and play online games with no lag but not anymore! Only when I started researching about noise signal and line attenuation did I come across some post about firmware update SG4B1000E020 and I checked mine and it was the same but updated on the 23rd! Never had any issues with my Internet for 1.5years until now. Contract coming to a end soon and don't think I'll be renewing with so many BF deals if BT doesn't do anything about this.
