If your iPhone stays connected to Wi-Fi while you’re using it but quietly drops the connection the moment the screen locks, you’re not imagining things. This usually happens because of power-saving behavior, network settings, or router compatibility — not a hardware problem.
The short version: when the phone locks, iOS sometimes reduces background network activity to save battery. If certain settings or network conditions aren’t ideal, the device may switch away from Wi-Fi or stop maintaining the connection entirely.
Start with Low Power Mode
This is the most common cause, and it’s easy to overlook.
- Open Settings.
- Tap Battery.
- Turn Low Power Mode off.
When Low Power Mode is active, iOS limits background tasks and network activity after the screen locks. Some routers interpret this reduced activity as inactivity and end the session.
Check Wi-Fi Assist
Wi-Fi Assist allows the phone to switch to cellular data if the connection looks weak. The switch often happens right after locking the screen because background signal checks behave differently.
- Go to Settings → Cellular.
- Scroll down to Wi-Fi Assist.
- Toggle it off temporarily and test.
If the disconnect stops happening, your Wi-Fi signal may be borderline rather than broken.
Disable Low Data Mode for That Network
Low Data Mode restricts background network usage, which can cause Wi-Fi sessions to pause when the device sleeps.
- Open Settings → Wi-Fi.
- Tap the ⓘ next to your connected network.
- Turn off Low Data Mode.
Lock the screen and wait a minute to see if the connection holds.
Forget and Rejoin the Network
Sometimes the saved network profile becomes slightly corrupted — especially after router updates or iOS upgrades.
- Go to Settings → Wi-Fi.
- Tap the network name.
- Select Forget This Network.
- Reconnect by entering the password again.
This rebuilds the connection from scratch and often fixes sleep-related drops.
Look at the Router Side
If multiple devices stay connected but only the iPhone disconnects during sleep, the router may still be involved. Some routers aggressively close idle connections or handle newer iOS power management poorly.
Try restarting the router first. If available, disable settings like “smart connect,” band steering, or aggressive power saving in the router admin panel. These features sometimes move devices between bands when activity slows down — which happens right after the screen locks.
Reset Network Settings (If Nothing Else Works)
This clears all Wi-Fi, VPN, and cellular configurations.
- Open Settings → General → Transfer or Reset iPhone.
- Tap Reset.
- Select Reset Network Settings.
You’ll need to reconnect to Wi-Fi afterward, but persistent lock-screen disconnect issues often disappear after this step.
One practical tip: after making a change, lock the phone for at least one minute before testing again. Wi-Fi sleep behavior doesn’t always change instantly.
If the connection now stays active while the screen is locked, the issue was almost certainly related to power or network configuration rather than the Wi-Fi hardware itself.