The short answer
Check the time zone and location in the app first, because a device set to the wrong region runs schedules at the wrong hour and sunset schedules at the wrong time entirely. Then check whether the plug was online when the schedule should have run, and whether a second schedule or routine is undoing it.
A smart plug schedule is a small piece of automation with a small number of ways to fail. Working through them in order takes a few minutes, and the activity log in the app usually points straight at the answer.
Cause 1: time zone and location
Schedules run against the device’s or the account’s notion of time. Two things go wrong:
- The account’s time zone is wrong, often set during initial setup and never corrected, which shifts every schedule by the difference.
- The home location is wrong, which matters for sunrise and sunset schedules. A location set to the wrong city produces sunsets at the wrong time, and the error changes through the year.
Check both in the app’s home or account settings. Also consider daylight saving transitions, which occasionally leave schedules an hour out until the device syncs.
Cause 2: the plug was offline
Cloud-scheduled plugs need to be reachable when the schedule fires. If the plug lost Wi-Fi, the schedule simply does not run, and there is no retry.
Check the plug's connection history in the app
Most show when it was last seen online.
Check the signal strength where the plug is
Smart plugs are often behind furniture or in a corner, which is the worst case for a 2.4GHz device with a tiny antenna.
Reserve a fixed IP address for it
In the router, which prevents disconnections when the lease expires.
Check the router's DHCP pool is not full
A full pool prevents the plug rejoining after a router restart, silently.
Check whether the schedule runs locally
Some plugs store schedules on the device and run them without the internet. Those are far more reliable, and it is worth knowing which type you have.
A plug that stores its schedule locally continues working during an internet outage; a cloud-scheduled one does not. If reliability matters, choose plugs that support local schedules or Matter, and test by disconnecting your router briefly and seeing whether the schedule still fires.
Cause 3: something else is controlling it
This is the most common cause after time zones. Smart plugs frequently end up controlled from several places at once:
- A schedule in the manufacturer’s app, and another routine in a voice assistant app.
- A routine created by another household member.
- An automation with a condition that no longer matches.
- A group action that overrides the individual device.
- A manual override left in place, since some plugs ignore schedules after a manual switch until the next cycle.
Choose one place to keep schedules and remove the duplicates elsewhere. Debugging automations spread across three apps is considerably harder than it needs to be.
Cause 4: power-on behaviour
After a power cut, many plugs default to on, which can make it appear that a schedule ran when it did not, or leave a device on that the schedule had turned off. Most plugs let you set the power-on state to off or last state, and doing so removes a confusing class of behaviour.
Cause 5: firmware and app updates
Schedules occasionally stop after a firmware or app update, sometimes because the schedule format changed and the old entries did not migrate. If everything else checks out, delete the schedule and recreate it, which is quicker than investigating further and frequently works.
Cause 6: the account
An account signed out, a re-authentication prompt unanswered, or a household member removed can stop schedules involving their devices. Open the app and confirm everything shows as connected, and check whether any integration is asking to be reconnected.
Never rely on a smart plug schedule for anything with safety implications: heaters, medical equipment, aquarium or vivarium heating, or anything that must not lose power. Schedules fail silently and plugs go offline. Use purpose-built equipment with its own thermostat and safety cut-out for those jobs.
Diagnosing efficiently
Set a temporary schedule for two minutes ahead and watch what happens. If it fires, the schedule system works and the original schedule’s timing or conditions are wrong. If it does not, the plug or the connection is the problem. That single test separates the two halves and takes three minutes.
Why does my schedule run at the wrong time?
The account’s time zone is wrong, or for sunset schedules the home location is. Both are set during initial setup and rarely revisited.
Does a smart plug schedule work without internet?
Only if the plug stores the schedule locally. Cloud-scheduled plugs need to be reachable when the schedule fires, and there is no retry if they were offline.
Why did my plug turn on after a power cut?
Most plugs default to on when power returns. Set the power-on behaviour to off or last state in the app if the option exists.
Can two schedules conflict?
Frequently. A schedule in the manufacturer’s app and a routine in a voice assistant app controlling the same plug is the most common cause of apparently random behaviour.
Why does my plug keep going offline?
Usually weak Wi-Fi where it is placed, or an IP address change. Reserve a fixed address in the router and consider whether the plug is behind furniture or in a corner.
The short version
Check the time zone and home location. Check whether the plug was online when the schedule should have fired, and reserve a fixed address for it. Look for a second schedule or routine controlling the same plug from another app. Set the power-on behaviour so a supply blip does not confuse things. And test with a schedule two minutes ahead, which tells you immediately which half of the problem you have.
