I've had a steady download and upload speeds of 40/6 Mb since 2014, except for last year when they dropped to 30/2 for 4 months, about the same time as I downgraded to Infinity 1 and bought a HH6 if I remember correctly. The speeds eventually came back up but now they've dropped off again, 28.9/2.4. What's complicating the problem is that since I bought a set of Sonos One speakers my HH6 started re-booting at least once a day. It got so bad that I couldn't complete the BT speed check. Googling indicates there is a problem with the HH6 and Sonos but I can't find any solutions. So I've reverted back to my old HH3 which, since I plugged it in, has stayed connected for just over 10 days. I thought the speeds would come back up after 10 days but they haven't. I ran another BT speed check and it says there's a fault and to re-start both the router and modem. I've done this in the past and it didn't change anything. Would you advise re-booting or wait a bit longer for the speeds to come back up?
unfortunately unless you have unlocked the modem all the meaningful stats sre held by the modem and not the HH3
the fewer resets the better as stability is the main thing you should be trying to achieve
this will help https://kitz.co.uk/routers/hg612hacking.htm