@DMUM Consider removing Satellite M9 and M3W from Deco mesh, in Deco app, so that you only have Main Deco M9 left. Then, change it to AP mode. I remember when I set up my Deco mesh, I started with...

@Roy-B On second thought, can you run one more test? Power off edge node in home office room, and from that room run speedtest with mobile device that is now connected by WiFi to one of two remaining...

@EricBoy Do you run your Deco mesh in Router mode or in Access Point mode? This is where to check it in Deco app:

@Roy-B You can not change which node Satellite node connects to, at least not in current X20 firmware. See TP-Link article on that topic: [Deco] Manual Signal Source Selection Scroll down to the...

@Roy-B Your edge node, is it connected to hallway node, or to main Deco node?

@_Btree019_ If you haven't changed talk talk router to "modem only" mode, you may not need to do that with bt. Also, do you run Deco mesh in Router mode or in Access Point mode? This is where to...