Switched 22/12/20 and had to wait 2 weeks for line to "stabilise", during which time had 3 periods (min 15 mins to max 120) of downtime.
Next advice was to get a replacement (of their) router, which certainly seemed to make a difference. When replaced wireless connection speed was 115mbps

However, since last Friday 08/01/21 when router replaced their speeds have varied between 4 & 84mbps and seems very inconsistent. Now waiting on Openreach to fix an external fault (if they can find and identify).
Edited by worldtravellerz (Tue 12-Jan-21 13:45:53)