TLDR: Problems getting a new Sonos component to connect to an existing system? Remove all old connection records from your router and switch off 5Ghz wifi (BT Smart Hub 2 router in the UK). This worked for me after more than 24 hours of trying
I thought I would post here in case it helps someone else with similar problems in the future with connecting new Sonos components to an existing (and old) system.
I have had a Sonos system for years and had a setup with a bridge, play:5, 2x play:3, 2x play:1, a Connect and finally a One. I traded in the Play:5 and Connect to buy two new Ones which were to replace the 5 in my kitchen.
Setup has always been fairly simple for other devices as I’ve bought them and added them to the system over the years but the new One’s just would not connect. I tried very many procedures outlined here and in other forums with no luck. In an effort to simplify the process, I removed the Bridge, reset everything and set up an entirely new system…. still no luck with the new components, either wireless or wired directly to the router.
My router is a BT Smart Hub2 (I live in the UK) and it is not possible to split the 2.4/5 GHz network SSID’s, so I switched 5Ghz off, still no luck. I unplugged/switched off everything in my home network to see if I was getting interference from something, still nothing. At this point, 24 hours had past over a weekend and it was a high possibility that Sonos were going to be refunding me for components which were useless to me.
I’m not an IT person but over the years have had to try to understand the basics, so I dug deeper in to the router settings and noticed that while the new components were failing at the final connection step in the app, they were being added to my home network. However, they were connecting as ipv6 devices and the rest of the system was connected using ipv4. To complicate things, there is no way to switch off ipv6 on the router.
While doing all this, I noticed that the connection records of all the old devices, including the Bridge were still in the routers connection table in a disconnected status. So, I removed all these disconnected device records, cycled the power on the router and tried to connect one of the new devices again (by this time it was directly wired to my router). To my complete surprise, it connected perfectly! I thought this was a fluke but I then powered up the other new device and it connected correctly over wifi.
This is a long way of hopefully helping others like myself from despair and hopefully saving some time and effort if you’ve got a similar setup to me. Good luck.….