Smart Connect node band steering encourages a wireless client to connect to a node's better connection/signal/band/SSID when using the same SSID for all bands.
It generally works, but it forces Auto settings for wireless mode, channel bandwidth, control channel, and extension channel... you can't fix your WiFi channels.
I find that the latest 86U firmware 45717 logs excessive channel scanning when using Smart Connect, so I have it disabled for now and am using separate SSIDs (OE and OE-24), which is equally seamless (or better) when the client only knows to connect to one band. I'll probably return to using Smart Connect and same SSIDs (OE) after a future firmware fix... or maybe not since I like fixing my WiFi channels... maybe a future firmware fix will fix this, too.
I've only used the default Smart Connect settings since they are beyond my understanding and desire to learn about them.