It reboots on its own, or switches off while a heavy load runs. Check whether it really restarted, then the scripts, schedules and firmware, then the load.
Checked
Gen4
Start here
What are you seeing?
Pick the closest match and we'll point you to the fix most likely to sort it.
A Shelly restarts when its firmware or a script crashes, when something tells
it to, or when its supply drops. Shelly turns off a crashing script by itself,
and after a reboot loop it starts in Safe Mode to break the cycle.
Overheating is different: the device stays on, but its overheating protection
switches the output off.
Before you start
These checks are done in the Shelly app, a browser or Home Assistant. Don't touch a device or wall plate that may be hot. If one smells hot or its breaker trips, leave it off at the switchboard and call a licensed electrician.
Quick checks first
Run these checks before moving on to the fixes.
Checklist0 of 3 checked
Check it really restarted
In Home Assistant, turn on the device's Uptime entity. Uptime counts the seconds since the last restart, so if it keeps counting through a drop-out, the device didn't restart.
Note when it happens
The same time every day, after a script change or under a heavy load each point to a different cause below.
Check the firmware version
On its web page, the version is in the footer. A blue update icon in the header means a newer stable version is out.
Fixes, most likely first
Work down the list and stop when it's fixed.
1
Most likely for you
A firmware bug is restarting it
How to tell. It restarts at random with nothing else changed. Shelly's own first check for repeated drop-outs is whether a device is rebooting because of power or firmware.
Update the firmware
On its web page, go to Settings, then Firmware, and click Check for updates. Recent releases include several crash fixes.
If the update won't go through
The firmware guide covers updates that fail or never show up.
Did this fix it?
2
Most likely for you
A script is crashing it
How to tell. It started restarting after a script was added or changed. Shelly turns off a script that crashes the device, so afterwards the script shows as stopped, with an error under its name.
Stop it running on startup
On its web page, click Scripts and turn off the toggle beside the script, so it doesn't start after the next restart.
Fix the script before running it again
The script guide covers reading the error and the usual causes, such as a loop that never ends.
Did this fix it?
3
Most likely for you
Something is restarting it on purpose
How to tell. It restarts at the same time each day, or when a routine runs. A Shelly schedule can run any command, including a reboot, and Home Assistant has a Reboot button for every Shelly.
Check the schedules
On its web page, click Schedules and check what each one does. Turn off or delete any schedule that reboots it.
Check Home Assistant and other apps
Look for an automation that presses the device's Reboot button in Home Assistant, or a routine elsewhere that does the same.
Expect a restart after some changes
Changing the MQTT settings, adding an Add-on or installing a firmware update restarts the device once. That's normal.
Did this fix it?
4
Most likely for you
It's in Safe Mode after a reboot loop
How to tell. After a run of restarts, it's back online but scripts and schedules don't run. Shelly starts in Safe Mode when it detects a reboot loop, with scripts, schedules and webhooks off for that boot.
Restart it normally
Safe Mode lasts for one boot only. On its web page, go to Settings and click Reboot.
Find what caused the loop
If it loops again, the cause is still there. Work through the firmware, script and power causes on this page.
Did this fix it?
5
Most likely for you
It isn't restarting, it's losing Wi-Fi
How to tell. Uptime in Home Assistant keeps counting through the drop-outs. The device stays on; only its connection drops.
Check the signal
On its web page, go to Settings, then Wi-Fi, and read the RSSI. The offline guide covers a weak signal and what to do about it.
Did this fix it?
6
Most likely for you
The supply is dropping out
How to tell. Uptime goes back to zero, and lights or appliances on the same circuit blink at the same time. Shelly lists unstable power as a cause of repeat restarts.
Ask an electrician to check the supply
The supply and the connections to the Shelly are wiring work for a licensed electrician.
Did this fix it?
7
Most likely for you
It's switching off to protect itself from heat
How to tell. The output switches off by itself while a heavy load runs, and the Device temperature entity in Home Assistant reads high. Every Gen4 relay and the Dimmer Gen4 have overheating protection.
Check the load against the rating
Shelly rates the 1 and 1PM Gen4 at 16 A, the 1 Mini and 1PM Mini Gen4 at 8 A, the 2PM Gen4 at 10 A per channel, and the Dimmer Gen4 at 200 W. A load near or over that needs a different device, which is a job for a licensed electrician.
Check where it's installed
Shelly rates the Gen4 range for indoor use at up to 40 °C around the device. A roof space or a spot beside a heat source can run hotter. Moving it is a job for a licensed electrician.
Did this fix it?
8
Most likely for you
An output protection switched it off
How to tell. On a 1PM, 2PM, 1PM Mini or Dimmer Gen4, the output switches off at about the same power each time. That's a limit you can set, not the heat.
Check the limits
On its web page, go to Settings, click the output, then Output protections (Protections on the Dimmer Gen4), and compare the limits with what the load draws.
Did this fix it?
On your device
Shelly Presence Gen4Its power adapter matters
Use a dedicated 5 V adapter
The Presence Gen4 runs from USB-C. Shelly says to use a good adapter with a steady 5 V, and to avoid multi-port chargers, charging stations and fast chargers, whose output can change as other devices are plugged in.
