@Jandj,

Smart Actions depend on their connection to the internet and cloud.

Have you made any recent changes to your network or security settings?

What is the status of the LED on the outlet

If you disconnect your phone from your Home Wi-Fi, are you able to control the plug? If not, it has become disconnected from the internet.

You may consider simply replugging the device, or performing a soft reset of the device, which would force the device to communicate with the cloud again but would save any settings, names, and automation you have set.

  @Jandj,

After they stop working, see if you can control the devices while not connected to your home Wi-Fi, or if you can even control them while connected to Wi-Fi.

What's the color of the outlet's LEDs at this point?

It is likely a setting with your router or network if it works for a while but then fails after a period. What router are you connecting the device to? It may be possible that a feature such as Beamforming is causing the problem. Do you have an IoT or Guest Network you could try?