DIR 880L with latest 1.07.WW FW.
When I select Smart Connect it also enables the 5 Ghz Guest Zone. I don't use the Guest Zone, but there is no way to disable it with Smart Connect enabled.
I checked this by making sure both 2.4 & 5 Guest Zones are disabled. Go back to WiFi and enable Smart Connect. I looked at the WiFi on my iPhone and there is a new SSID for the 5 Ghz guest.
Go back into router and disable Smart Connect, look at the Guest Zone and find the 5 Ghz enabled.
To prevent using Guest Zone I cannot us Smart Connect.