Is it possible to switch off the WiFi in SENSE? I have not found an option to do so in the app.
No it's not possible and if you could, then i don't think you would be able to access the app on you phone anymore, so it's propably by design that wifi cannot be turned off.
It is not possible to turn off the WiFi connection on your F-Secure SENSE router but it is possible to turn off the Guest Network. You may choose to hide your WiFi network if the aim is to prevent it from being seen during random wifi search.
Actually you could still manage a Sense without WiFi with the phone, if you plug-in a different WiFi access point. Then you could use the Sense with the cable as a firewall and internet protection device. That’s how I use it.
My Sense starts dropping off the WiFi connection repeatedly and regularly when around 8 or more WiFi devices connect to it. So I can’t use it as a WiFi access point. I use a different WiFi access point device that handles all IoT WiFi devices, phones, tablets, etc without a problem.
The Sense is an excellent wired device and I wish I could disable the WiFi module to reduce airwave congestion.
If someone disables WiFi and needs it back, they could always press the reset button.