Eero, IPv6, and Sub solution. I just moved and I feared we would have Sonos issues like I read about on here because of the new setup. We switched from a nighthawk router to an eero mesh system. I love it’s ease. Everything added and played, even the new Five I bought for the turntable. However, after a day, the arc kept disappearing from the options, and then would appear with +? instead of sub. Reinstall of sub didn’t work until I entered its code. It worked sometimes, just wouldn’t be named. I researched, Sonos has a lot of info, and so do threads, but I quaked at the idea of making ip changes to the system or moving devices and looking for interference, so I explored the eero app and saw that the IPv6 option was auto selected No and changed it. Restarted and bam, no issues!