Xiaomi Mobile Data Stops Working After Network Switch

Xiaomi Mobile Data Stops Working After Network Switch – UK Fix

This guide helps if your Xiaomi mobile data stops working after switching from WiFi to mobile data, switching between two SIM cards, or moving between network coverage areas.

Quick Answer:
If your Xiaomi mobile data stops working after a network switch, first toggle Airplane mode ON for 30 seconds, then OFF. This forces your phone to reconnect to the mobile network. Then check that Mobile Data is ON and Data Saver is OFF. If the problem happens every time you leave WiFi, forget the WiFi network and reconnect later to rule out a stuck WiFi handover.

Applies to Redmi, POCO and Xiaomi Phones

This guide applies to Xiaomi, Redmi and POCO devices running MIUI or HyperOS on all UK carriers – EE, O2, Vodafone, Three, and their MVNOs.

🔍 Quick Diagnostic Table – Does Airplane Mode Fix It?

Use this table to quickly identify your issue:

If this happensUsually means
Airplane mode fixes it every timeNetwork registration problem
Restart fixes itTemporary HyperOS issue
Only WiFi switch causes itWiFi handover issue
Only moving between areas causes itMast handover problem
Nothing fixes itCarrier or SIM issue

🔍 Quick Start – Find Your Path

SymptomMost Likely CauseGo To
Data stops after leaving WiFiWiFi to mobile handoverSection 1
Data stops after switching SIMsDefault data SIM changedSection 2
Data stops after moving locationMast handoverSection 3
Data stops randomly after any switchNetwork registration issueSection 4
Data stops after HyperOS updateSettings resetSection 5

Before You Start

Before going through the sections, try this quick sequence:

  • Toggle Airplane mode – ON for 30 seconds, then OFF.
  • Check Mobile Data is ON – Settings → SIM cards & mobile networks → [Your carrier] SIM → Mobile data → ON.
  • Turn off Data Saver – Settings → SIM cards & mobile networks → [Your carrier] SIM → Data saver → OFF.
  • Restart your phone – A full reboot can resolve temporary glitches.

If these don't work, continue to the relevant section below.

Section 1 – Data Stops After Leaving WiFi (WiFi to Mobile Handover)

If mobile data stops working when you leave a WiFi network (e.g., leaving home or work), the phone may fail to switch from WiFi to mobile data correctly.

Try these in order:

  1. Toggle Airplane mode – ON for 30 seconds, then OFF. This forces reconnection to mobile data.
  2. Turn WiFi OFF manually for one minute before leaving coverage – Sometimes HyperOS stays on weak WiFi and doesn't activate mobile data.
  3. Check Mobile Data is ON – Settings → SIM cards & mobile networks → [Your carrier] SIM → Mobile data → ON.
  4. Turn off Data Saver – Settings → SIM cards & mobile networks → [Your carrier] SIM → Data saver → OFF.
  5. Disable Smart Network Switching – Settings → Connection & sharing → Network settings → Turn OFF "Auto switch between WiFi and mobile data" (if available). This prevents the phone from automatically switching, which can sometimes cause issues.
  6. Restart your phone – A full reboot can resolve temporary handover glitches.

Section 2 – Data Stops After Switching SIMs (Dual SIM)

If you have two SIMs and data stops after switching which SIM is used for data, the issue is usually the default data SIM setting.

Try these in order:

  1. Check default data SIM – Settings → SIM cards & mobile networks → Default for mobile data → Ensure the correct SIM is selected.
  2. Check Mobile Data is ON for both SIMs – Settings → SIM cards & mobile networks → [SIM1] → Mobile data → ON. Repeat for SIM2.
  3. Switch back to the previous SIM – If data worked before the switch, switch back to test if the issue is SIM-specific.
  4. Wait 30–60 seconds after changing the default data SIM before testing – The network may need time to register the change.
  5. Toggle Airplane mode – ON for 30 seconds, then OFF. This forces reconnection with the new data SIM.
  6. Reset APN for the new data SIM – Settings → SIM cards & mobile networks → [New data SIM] → Access Point Names → three dots → Reset to default → Restart.
  7. Restart your phone – After switching data SIMs, a reboot often resolves connection issues.

Section 3 – Data Stops After Moving Location (Mast Handover)

If data stops when you move between locations (walking, driving, or travelling), the phone may be struggling to switch between masts.

Try these in order:

  1. Toggle Airplane mode – ON for 30 seconds, then OFF. This forces reconnection to the nearest mast.
  2. Switch to 4G – Set Preferred network type to 4G/3G/2G auto. 5G handover can be less stable.
  3. Disable 5G temporarily for several hours – This helps determine whether the problem only affects 5G handovers.
  4. Check carrier coverage – If the issue only occurs in specific areas, coverage may be weak.
  5. Check for carrier settings updates – Some network configuration updates are delivered separately from HyperOS updates through your carrier or Google Carrier Services.

Section 4 – Data Stops Randomly After Any Switch (Network Registration Issue)

If data stops after any type of switch and Airplane mode temporarily fixes it, the issue is likely network registration.

Try these in order:

  1. Search for your network manually – Settings → SIM cards & mobile networks → [Your carrier] SIM → Network operators → Turn off "Choose automatically" → Search → Select your carrier manually.
  2. Reset APN to default – Settings → SIM cards & mobile networks → [Your carrier] SIM → Access Point Names → three dots → Reset to default → Restart.
  3. Check preferred network type – Settings → SIM cards & mobile networks → [Your carrier] SIM → Preferred network type → Select 5G/4G/3G auto.
  4. Disable Private DNS temporarily – Settings → Connection & sharing → Private DNS → Off.
  5. Check IMEI – Dial *#06# to display your IMEI number. If it shows "Unknown" or "Null", network registration may not be possible – contact Xiaomi support.
  6. Reset network settings – Settings → Connection & sharing → Reset Wi-Fi, mobile networks, and Bluetooth (removes saved Wi-Fi passwords).
  7. Test your SIM in another phone – If the problem follows the SIM, contact your carrier.

Section 5 – After a HyperOS Update

If data started stopping after network switches following a HyperOS update, the update may have reset settings.

Try these in order:

  1. Reset APN – Section 4.
  2. Check preferred network type – Set to 5G/4G/3G auto.
  3. Disable Smart Network Switching – Section 1.
  4. Check whether a carrier settings update has been installed automatically – Many users don't realise Carrier Configuration is separate from HyperOS.
  5. Reset network settings – Section 4.
  6. Reboot twice – Some updates require a second reboot to fully apply changes.

Why Does Mobile Data Stop After Network Switch?

  • WiFi to mobile handover failure – The phone doesn't switch to mobile data correctly.
  • Default data SIM changed – In Dual SIM phones, the wrong SIM may be selected for data.
  • Mast handover failure – Switching between masts can cause temporary disconnection.
  • Network registration issue – The phone fails to re-register on the network after a switch.
  • VPN or Private DNS preventing reconnection – After network changes, some VPNs or DNS settings may block reconnection.
  • Settings reset – After updates, APN or network preferences may change.
  • Smart Network Switching – This feature can sometimes cause handover issues.

⚠️ What NOT to Do

  • Don't factory reset your phone – This is rarely needed.
  • Don't assume your phone is broken – Test your SIM in another phone first.
  • Don't ignore Airplane mode – It's the quickest and most effective fix for handover issues.

Quick Questions

Why does my Xiaomi data stop when I leave WiFi?
This is usually a handover issue. Toggle Airplane mode or disable Smart Network Switching.

Why does my data stop after switching SIMs?
Check that the correct SIM is set as default for mobile data.

How do I fix mast handover issues?
Toggle Airplane mode or switch to 4G.

Will resetting network settings fix this?
It can help if settings are corrupted. Try other fixes first.

Why did this start after a HyperOS update?
The update may have reset APN or network preferences. Check your settings.

Can WiFi Calling affect mobile data switching?
Normally no, but temporarily disabling WiFi Calling can help identify whether it is interfering with network handover.

Why does Airplane mode always fix the issue?
Because it forces the phone to register again with the carrier instead of continuing to use an invalid network session.

Does Dual SIM make this problem more common?
Yes. Incorrect default data SIM settings or simultaneous network switching can interrupt mobile data.

Why does this only happen when travelling?
Because your phone repeatedly switches between different mobile masts. If the handover fails, mobile data may stop working until the phone reconnects.

I can't find Smart Network Switching on my Xiaomi. Is that normal?
Yes. Not all Xiaomi or HyperOS versions include this feature. If it isn't available on your device, simply continue with the other troubleshooting steps.

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