This is one of the most consistently reported issues across the Samsung Galaxy lineup, and it is frustrating in a specific way everything works fine while you are actively using the phone, but the moment the screen turns off, Wi-Fi drops. Notifications stop arriving, background sync pauses, and when you wake the phone it takes several seconds to reconnect. The good news is that every common cause of this problem has a specific fix, and most users resolve it within the first two or three steps below.
Why Samsung Galaxy Phones Disconnect From Wi-Fi During Sleep
The root cause is almost always power management. Samsung's One UI aggressively manages background connections to extend battery life, and Wi-Fi is one of the connections it will reduce or cut during sleep if not configured correctly. The phone is not malfunctioning it is doing exactly what it was designed to do. The fix involves telling it that Wi-Fi is a connection you want maintained even when the screen is off.
Step 1: Turn Off Wi-Fi Power Saving Mode
This is the most common cause of the problem and the first thing to check.
Open Settings, then tap Connections, then tap Wi-Fi. Tap the three-dot menu in the top right corner and select Advanced. Look for Wi-Fi power saving mode or Intelligent Wi-Fi and make sure it is toggled off. When this setting is enabled, One UI reduces Wi-Fi activity during sleep to conserve battery. Disabling it keeps the connection active while the screen is off.
On newer One UI 8 and One UI 8.5 devices, this setting may appear under Settings, then Connections, then Wi-Fi, then the three-dot menu, then Advanced settings. The location varies slightly depending on the Android version and One UI version your phone is running.
Step 2: Disable Adaptive Wi-Fi or Wi-Fi Auto Switch
Some Samsung Galaxy phones have a feature called Adaptive Wi-Fi or Switch to Mobile Data, which automatically switches to mobile data when the Wi-Fi connection quality drops below a certain threshold. This can cause the phone to silently disconnect from Wi-Fi in situations where the signal is technically present but weak, such as when you are at the far end of your home from the router.
Go to Settings, then Connections, then Wi-Fi, then the three-dot menu, then Advanced settings. Look for Switch to mobile data or Adaptive connectivity and turn it off. This prevents One UI from automatically routing traffic away from Wi-Fi during sleep based on signal strength assessments.
Step 3: Check Adaptive Battery Restrictions for Apps
Samsung's Adaptive Battery feature can restrict background network activity for specific apps, which can prevent apps from receiving data over Wi-Fi while the phone is asleep even when the Wi-Fi connection itself is maintained. If you are specifically noticing that certain apps stop updating in the background messaging apps not delivering notifications, email not syncing this is often the cause.
Go to Settings, then Battery, then Background usage limits or Sleeping apps. Review the list of restricted apps. If any app that requires background connectivity is listed there, tap and hold it and select Remove to allow it to run normally in the background.
Step 4: Disable Battery Optimization for Persistent Apps
For apps that need to maintain a persistent connection in the background messaging platforms, email clients, VPN applications Battery optimization can interrupt their network activity during sleep even when Wi-Fi is connected. Adjusting this per app gives you more precise control.
Go to Settings, then Apps, then select the app you want to adjust. Tap Battery, then select Unrestricted. This tells One UI to allow the app full background network access regardless of sleep state. Only apply this to apps that genuinely need it, as Unrestricted background access will have a small but real impact on battery life.
Step 5: Check Your Router's Client Isolation and DHCP Lease Time
Not all Wi-Fi disconnection issues on Samsung Galaxy phones are caused by the phone itself. Some home routers have settings that contribute to the problem.
Client isolation, when enabled on a router, prevents devices on the same network from communicating with each other and can cause some Samsung devices to disconnect during sleep periods. Check your router's admin settings typically accessed via a browser at 192.168.0.1 or 192.168.1.1 and disable client isolation if it is enabled.
DHCP lease time is another factor. A very short DHCP lease time means your router reassigns IP addresses frequently, which can cause a brief disconnection when the phone wakes from sleep and requests a new lease. Extending the DHCP lease time to 24 hours or longer in your router settings prevents this from happening.
Step 6: Forget and Reconnect to Your Wi-Fi Network
If the previous steps have not fully resolved the issue, forgetting the network and reconnecting from scratch can clear a corrupted network profile that is causing intermittent disconnections.
Go to Settings, then Connections, then Wi-Fi. Tap and hold your network name, then select Forget network. Reconnect by tapping the network name, entering your password, and letting the phone complete a fresh connection setup. This clears any saved configuration that may be contributing to the problem.
Step 7: Check for a Software Update
Samsung regularly releases software updates that address known connectivity bugs. A Wi-Fi disconnection issue that appeared after a specific One UI update may already have a fix available that has not yet reached your device.
Go to Settings, then Software update, then Download and install. Install any available update and check whether the Wi-Fi behavior improves afterward.
Step 8: Reset Network Settings as a Last Resort
If none of the above steps resolve the issue, resetting all network settings returns Wi-Fi, Bluetooth, and mobile data configurations to factory defaults. This will remove all saved Wi-Fi passwords and paired Bluetooth devices, so make sure you have your Wi-Fi passwords available before proceeding.
Go to Settings, then General management, then Reset, then Reset network settings, then confirm by tapping Reset settings. After the reset, reconnect to your Wi-Fi network and monitor whether disconnections continue. In most cases, this resolves persistent Wi-Fi issues that software and individual setting adjustments did not fix.
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