You set up an old Samsung Galaxy as a security camera. It is plugged in, the screen is off, it is recording. You check it in the morning and the recording stopped somewhere around 3 a.m. Nothing crashed. There was no power cut. The phone simply restarted itself, and after the restart nothing was recording.
On many Galaxy phones this is not a fault. It is a setting, and Samsung documents it. This guide explains what the setting does, why a camera phone is exactly the kind of phone it picks, and how to check and turn it off on your own phone in about two minutes. It is written for a simple setup: one old Android phone, no cloud account, no subscription.
Why does my Samsung phone restart by itself at night?
Most likely because of Auto restart, a Samsung maintenance feature that restarts the phone on a schedule or "when needed." Samsung's own support pages describe it in two places, depending on the phone model and One UI version:
- Settings → Battery and device care → ⋮ (More options) → Automation → Auto restart at set times. Samsung's Philippines support page says: "Your phone will restart automatically within 1 hour of the time you set."
- Settings → Device care → Auto optimisation → Auto restart, with two switches: Restart when needed and Restart on schedule. Samsung's Hong Kong support page (updated 8 September 2026) says Restart when needed will restart the device "when memory usage increases or if it has not been restarted for a period of time."
Samsung also says on both pages that menus "may vary depending on the device model and software version." So on your phone the names may be slightly different. The search box at the top of Settings is the quickest way to find it: type restart.
Why a camera phone is the perfect target for Auto restart
Samsung lists the conditions under which the phone will restart itself. From the Philippines support page, the phone will only restart when:
- "The screen is off."
- "The phone isn't being used."
- "The battery is above 30%."
- "SIM card lock is off."
The Hong Kong page says the same thing in shorter form: "By default, the screen must be off and the battery level must be at least 30%."
Now look at a phone doing camera duty:
| Samsung's condition | A normal phone at 3 a.m. | An old phone used as a camera |
|---|---|---|
| Screen is off | Usually | Always — screen-off recording is the point |
| Battery above 30% | Sometimes | Always — it is on the charger 24/7 |
| SIM card lock off | Usually | Almost always — many camera phones have no SIM at all |
| Phone isn't being used | Usually | Unclear — see below |
The first three conditions are not "sometimes true" for a camera phone. They are true by design, every night. The battery rule is the interesting one: the 30% condition protects a phone that is running low, but a camera phone that never leaves the charger never falls below it. The setup that keeps your camera reliable (plugged in, screen off) is the same setup that makes it eligible for an automatic restart.
The fourth condition, "the phone isn't being used," is the one nobody can answer for you. Samsung does not define it on these pages. A recording app running in the background with the screen off might count as "use," or it might not, and it may differ between phones and software versions. I am not going to guess. The honest answer is: test your own phone, which is the last section of this guide.
What actually breaks after the restart
A restart takes a minute or two. Losing a minute of footage is not the real problem. The real problem is what the phone is like after it comes back.
Samsung says it plainly on the Hong Kong page, under Restart when needed: "You must unlock your device to check messages and notifications normally after it restarts."
That sentence is about messages, but the same rule applies to a camera. After any restart, Android starts in a locked state until someone enters the PIN, pattern or password. Android's developer documentation calls this Direct Boot mode and says: "By default, apps don't run during Direct Boot mode." An app only runs in that state if its developer built it to. So in an empty house or a closed shop, the phone may sit on the lock screen for days, waiting for a finger that is not coming.
We went through that state in detail, with Google's exact wording, in The Restart Nobody Scheduled: Direct Boot, and What an Unattended Android Camera Cannot Do. This guide is the Samsung-specific half: the restart that Samsung schedules for you, and the switch that turns it off.
How to turn off Auto restart on a Samsung camera phone (step by step)
Do this on the camera phone itself, while you are standing next to it.
Newer menu (Battery and device care):
- Open Settings.
- Tap Battery and device care (on some phones just Device care).
- Tap the three dots at the top right.
- Tap Automation.
- Tap Auto restart at set times and turn it off.
- While you are in Automation, look at the other items too. If there is an Auto optimise daily or similar option, read what it says it does before leaving it on.
Older or regional menu (Auto optimisation):
- Open Settings → Device care.
- Tap Auto optimisation.
- Tap Auto restart.
- Turn off Restart when needed.
- Turn off Restart on schedule.
Cannot find it? Use the search box at the top of Settings and type restart or optimis. The menu names change between One UI versions, but the search usually finds them.
Turning it off does not stop every restart
Samsung is clear that the switches do not cover everything. From the Hong Kong page:
- "Even if both Restart when needed and Restart on schedule are turned off, a system restart may still occur depending on your device's condition."
- "Emergency security updates may restart the device automatically even when automatic software download settings are turned off, depending on your country or region."
App updates from Google Play are a separate path again. An update can close a running app, and whether it comes back is up to the app. That is covered in The Update You Did Not Schedule: What Google Play Does to a Running Camera Phone.
So treat "Auto restart off" as removing the scheduled, every-night restart, not as a guarantee that the phone never restarts. The goal is to remove the restart that happens on purpose, and then know what your phone does after the ones you cannot remove.
If you want to keep a scheduled restart
Samsung recommends regular restarts to stop a phone getting slow, and on a very old phone that advice may be sensible. If you want to keep it, make it work for you instead of against you:
- Pick a time when you are usually there. For a shop camera, a time just after you open in the morning. For a home camera, a time when someone is normally awake. Then the person who is there can unlock the phone and check the camera is running again.
- Remember the one-hour window. Samsung says the restart happens "within 1 hour of the time you set," not exactly at that time. If you set 9:00, expect anything from 9:00 to 10:00.
- Use weekly, not daily. If your menu lets you choose days, one restart a week is one gap a week instead of seven.
- Turn it off before you travel. A locked house for a week, with nobody to unlock the phone, is the worst case. (Our Diwali travel guide has the rest of that checklist.)
The 10-minute test: what does your camera do after a restart?
This is the part that answers the question Samsung's pages leave open. Do it once, on the actual camera phone, with the actual app you use.
- Start recording the normal way and turn the screen off.
- Note the time.
- Restart the phone yourself (hold the side key, or pull down the quick panel and tap the power icon, then Restart).
- Do not unlock it. Leave it on the lock screen for 5 minutes. This copies what happens at 3 a.m.
- Check from another device. If your app has a live view over Wi-Fi, try to open it from a second phone or laptop on the same Wi-Fi.
- Now unlock the phone and look at the recordings. Is there a new file that started after the restart? Or does the last file end at the time you noted?
- Write down the result. "Recording came back without unlocking", "came back only after unlocking", or "did not come back until I opened the app". All three are possible, and they depend on the app and the phone, not on you.
If the answer is anything except the first one, the setting in this guide matters a lot for your setup, and so does who can reach the phone to unlock it.
Quick checklist for a Samsung camera phone
- [ ] Auto restart at set times: off (or set to a time when someone is there)
- [ ] Restart when needed / Restart on schedule: off, if your phone has them
- [ ] Restart test done; you know what your camera app does after a restart
- [ ] Battery checked, so a power cut does not also become a restart (how to check an old phone's battery)
- [ ] Play Store auto-update decision made for the camera app
If you are setting up a phone camera for the first time, start with Turn an old Android phone into a screen-off security camera (no cloud, LAN-only), then come back to this checklist before you leave the phone alone.
Sources
- Samsung Philippines support — Restart your Galaxy phone regularly to prevent it from slowing down or freezing (Auto restart at set times, the one-hour window, the four conditions)
- Samsung Hong Kong support — What to do if your Samsung Galaxy device appears to keep restarting (Auto optimisation, Restart when needed, Restart on schedule, restarts that still happen)
- Android Developers — Support Direct Boot mode
Background Camera RemoteStream turns an Android phone into a screen-off camera: it records with the screen off and keeps recordings on the phone, with no cloud account needed. Its Pro tier adds a live browser view over your own Wi-Fi and YouTube Live streaming; check the Play listing for what is free and what is Pro.
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