Hi @Brynbuga
It depends on the age/model of the speakers you have. Some units will only connect to 2.4 GHz, but as they have 5GHz radios (reserved for stereo pairing and Home Theatre binding), your router is mistakenly identifying them as devices willing to connect to 5GHz and thus tries to “band steer” them to a 5GHz connection which they refuse, and they then reapply for a connection. What all this boils down to is that the speaker, when initially connecting or refreshing an existing connection, can take a bit longer than it should to get connected.
You can see which speakers are willing to connect to 5GHz (when not bonded to another speaker in some way) on our Sonos system requirements help page, under “Supported Wi-Fi modes and security standards”.
One option is to split the 2.4GHz and 5GHz bands on your router so they don’t have identical SSIDs (broadcasted network name). I recommend just adding -5 to the end of the SSID for 5GHz. You will then need to teach your smartphones and other devices the new details for them to connect to 5GHz, but they will still connect to 2.4GHz automatically. If Sonos doesn’t know these credentials, then it will only ever connect to 2.4GHz.
Another option is to wire one Sonos product to ethernet permanently. This will create a mesh WiFi just for Sonos that all other Sonos devices will prefer over any WiFi from your router, and each connected unit will expand the range of the mesh they create. Note that Sonos Roam and Sonos Move will not utilise SonosNet, but they will both connect to 2.4 or 5GHz anyway. If your router is in a location where you do not want a speaker, then there is the Sonos Boost which will do the same job and is cheaper than a speaker. I would recommend you split the bands on your router rather than spending more money, however.
Any wired unit (or unwired, for that matter) should be kept 1m away from the router and other sources of interference to maximise Sonos reliability and performance.
Incidentally, many routers come preconfigured to have their 2.4 and 5 GHz bands separated in this way, and it seems to mostly be ISP-supplied routers that don’t, for whatever reason (at least, in my own experience). I wouldn’t describe it as suboptimal, just alternatively configured. Nor would I describe our software as buggy - Sonos operated in exactly this fashion long before many routers provided 5GHz as an option, and before any of them were powerful enough to transmit across a home, as we need them to do (hence the Bridge or another wired unit being a necessity in the old days). For compatibility reasons, we were unable to change most of this functionality until the advent of S2, but it depends on hardware limitations of older units too. Now, things are changing, but mostly with the newer models.
I hope this helps you understand how things currently stand.