@krn07 Have you tried temporary moving the Deco 4 and connecting it via LAN cable to the 1st floor switch, if it works then it would indicate that either an issue with the LAN cable or the 2nd floor...

@Kev205 ok cool, was going to say make sure the IPV6 is working with the smart hub, if not then like you say there is an issue at BT's side. I get 10/10 for my IPV6 test. Cheers

@Kev205 Im with BT FTTP 500mb connection and connect directly to my ONT with my Deco M9 plus, these are my IPV6 settings and it works fine.

@David-TP Following this post my Deco X60 has been working well, however there are times when the X60 loses connectivity to the network and reconnects, this is fine as i know the reason for the loss...

@Madascanbe What does your network setup look like?

@INFO404AK I tried the same a few months ago with my C80 and 2x Deco M9 plus units with a switch. I also got a network loop so gave up and changed my setup removing the C80. It could be your switch...