Just bought a 3 disc M5 Deco mesh system.  Setup finds the deco OK, then connects to the internet (i.e.if I plug a cable into the second port on the Deco, I get internet)  In the final stages of setup, though, (when it says "let's create your wireless network) it fails with the message "Failed to connect to TP link cloud"  

Someone suggested it might be a firewall issue, but even with the firewall disabled it behaves the same.

I am using Plusnet fibre with their Hub One router, and one forum suggests that's where the problem lies.  I spoke to Plusnet, but their starting point was "what's a mesh system?"  and it only got worse from there, so they're not able to help at all.

I also saw some posts about using an old modem to set up, but I can't do that either.  Surely, it can't be that a modern fibre router is incompatible with some of the latest mesh technology!?  I've done the setup about 20 times now, with various combinations of restarting both the router and the Deco, but its the same every time.

I've sent a mail to TP link support, but I'm pessimistic that will help.  

I'll  be both impressed and very grateful if anyone can help.