I'm hoping I can get some advice. I don't understand a whole heap about networking, but have had a Deco M5 Mesh system running successfully for a couple of years on BT Fibre using a Vigor 130 in place of the BT Smart Hub 1 and getting a robust reliable 72-75 Mbps over wifi and/or wired to an M5.

I've recently had FTTP put in (BT Full Fibre 100), so out with the Vigor and the ONT connected directly to the main M5 (BT haven't sent a new router yet, so no router in place as yet).
Checking the internet speed on the Deco app, it's showing a healthy 156 Mbps, however, using wifi, I'm only still only seeing a max of around 75 using Broadband Speedchecker, on a moble or laptop. Wired I'm seeing a small improvement, but the internet / wifi load is really small.

I was expecting to see a massive difference in performance, but sadly it seems to be about the same. Firmware is up to date and QOS set at 1000Mbs / Standard. I've rebooted the Decos and no change.