Why Xiaomi Mi Band 4 is off the phone: all the reasons and ways to eliminate

The Xiaomi Mi Band 4 fitness bracelet remains one of the most popular wearables due to its combination of functionality and affordable price, but many users face an annoying problem: the bracelet arbitrarily disconnects from the smartphone, loses synchronization or completely ceases to appear in the list of connected devices, the reasons for this behavior can be hidden in hardware malfunctions and software failures – from outdated firmware to conflicts with background applications.

In this article, we’ll look at all the possible causes of Mi Band 4 shutdowns, including rare cases that aren’t mentioned in the official instructions, how to diagnose a problem, what settings to check first, and what to do if the bracelet “gluts” even after reset, and focus on the hidden features of the Mi Fit app that help stabilize the connection.

If your bracelet only turns off in certain situations (such as during training or when your phone screen is locked), this may indicate a specific reason, and we have compiled a checklist for quick diagnosis and prepared step-by-step instructions for each scenario, from banal reboot to flashing the device.

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1. Bluetooth problems: the main reasons for the communication break

In 80% of cases, the Mi Band 4 disconnects from the phone due to an unstable Bluetooth connection, and the bracelet itself and the smartphone can be to blame – especially if it has custom firmware installed or many background applications running.

The first thing to check is the Bluetooth version on your phone. Mi Band 4 officially supports Bluetooth 4.2, but it works most stable with Bluetooth 5.0 devices.+. If your smartphone Released before 2017, frequent communication interruptions due to an outdated module are possible.

Another common cause is conflict with other Bluetooth devices, for example, if a wireless headphone, smartwatch and speaker are connected to a phone at the same time, the system may “discard” the bracelet as the least priority device.

• 📱 Check the Bluetooth version in your phone settings: Settings → The phone. → Information on the PO → Bluetooth version. If below 4.2, upgrade your firmware or consider buying a new smartphone.
• 🔄 Turn off all unnecessary Bluetooth devices before you plug in the bracelet. Sometimes even temporarily turning off the headphones helps.
• 🛠️ Reset Bluetooth settings on your phone: Settings → System system → Reset → Reset network settings (on Android) or Settings → Bluetooth → Forget this device (on iOS).
• 📶 Check for interference: microwave ovens, 2.4GHz Wi-Fi routers, and even some of them. LED-Lamps can interfere with Bluetooth.

⚠️ Attention: On iPhone with iOS 16+ There's a bug that can turn off the Mi Band 4 when you lock the screen, so the solution is to turn off Battery Optimization for the Mi Fit app in the battery settings.

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2. Mi Fit app crashes: hidden settings and errors

The Mi Fit app is the main intermediary between the bracelet and the phone, and its malfunction often leads to a loss of connection, for example, after updating the application, the cache may be lost, or background synchronization will be blocked by the battery optimizer.

One little-known reason is regional settings: If Mi Fit selects a region other than your actual location (e.g. China instead of Russia), the bracelet may periodically reset the connection due to conflicting time zones or sync servers.

Also check if the Mi Fit is powered by Bracelet Savings mode, which is only supported when you're using it actively, and in the background, the bracelet falls asleep and may appear to be off.

• 🌍 Check out the region in Mi Fit: Profile → Settings → Region. Choose your country.
• 🔋 Turn off the charge saving: Mi Band 4 → Saving charge → Off.
• 🗑️ Clear the app's cache: Phone settings → Annexes → Mi Fit → Memory. → Clear the cache.
• 🔄 Update Mi Fit to the latest version.Older versions (below 4.6.0) have a critical bug with a communication cliff.

Checking the region in settings|Cleaning the app cache|Disabling the charge savings|Update Mi Fit to the current version|Permit verification (geolocation, notifications)

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If the problem persists after these actions, try linking the bracelet to another Mi Account. Sometimes crashes occur due to a damaged user profile on Xiaomi servers.

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3. Hardware malfunctions: when the bracelet itself is to blame

If software methods did not help, the problem can lie in the physical damage of the Mi Band 4. Most often suffer: Bluetooth module (after falls or moisture), battery (when bloated, it presses on the antenna), charging contacts (oxidation leads to power failures and communication breakdown).

Pay attention to the symptoms:

The bracelet turns off when the hand moves (possibly damaged antenna plume).

The connection disappears when the charge level is below 30% (wear-out battery).

After charging, the bracelet works normally, but after 10-15 minutes it turns off (a problem with the power controller).

⚠️ Warning: If the bracelet stops turning on after water hits, DO NOT plug it into charging - this may cause a short circuit. First, dry the device in rice or silica gel for at least 24 hours.

To check for hardware problems, you can use the Mi Band 4 test mode:

1. Unplug the bracelet from your phone.
2. Press and hold the touch button for 10 seconds until the screen with the firmware version appears.
3. Press the button 5 times in a row - the bracelet will go into diagnostic mode.
4. Scroll the screen up/down to check the display and Bluetooth module.

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4. Firmware and update conflicts

Unstable firmware is one of the main reasons for spontaneous Mi Band 4 shutdowns, especially for Chinese firmware bracelets (versions below 1.0.9.54) that are not adapted for international use.

Problems can also occur after a failed update via Mi Fit. If the process is interrupted (for example, due to battery discharge), the firmware can become damaged, which will lead to constant reconnections.

Another nuance: some custom firmware (for example, Amazfit or Notify & Fitness) conflict with the original Xiaomi software, causing Bluetooth malfunctions.

• 📲 Check the firmware version: in Mi Fit go to Profile → Mi Band 4 → Firmware update.
• 🔄 Reverse to the stable version if after the update, failures began. To do this, download the archive with firmware 1.0.9.54 (the most stable) and run through Mi Fit.
• 🚫 Remove custom firmware if installed through Notify & Fitness or Tools & Mi Band.
• 🔌 Hand-write the bracelet through Mi Band 4 Tools (requires PC and firmware cable).

If after firmware bracelet stopped turning on, try hardware reset:

1. Connect the bracelet to the charger.
2. Press and hold the touch button for 20 to 30 seconds until you feel the vibration.
3. Release the button and the bracelet should reset.

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5. The Impact of Third-Party Applications and Optimizers

Many users do not realize that background applications can block the work of Mi Band 4.

— Battery optimizers (e.g. Greenify or built-in) MIUI),

Antiviruses (e.g. Avast or 360 Security)

Memory cleaning applications (e.g. Clean Master)

These programs can force Mi Fit to close or restrict its access to Bluetooth, which leads to a communication breakdown, and problems arise if the phone is power-saving mode, which limits the background activity of all applications, including synchronization with the bracelet.

There’s a hidden setting on Android that can help: disabling battery optimization for the Mi Fit.This will allow the app to run in the background without restrictions.

• 🔋 Turn off optimization for Mi Fit: Settings → Annexes → Mi Fit → Battery → Optimizing the battery → No restrictions.
• 🛡️ Add Mi Fit to the antivirus exceptions (if installed).
• ⚡ Turn off the power saving mode in the phone settings.
• 📱 Check the permissions for Mi Fit: Settings → Annexes → Mi Fit → Permissions (must be included: geolocation, Bluetooth, autorun).

Settings → Battery and productivity → Battery consumption management → Secure applications

This will prevent the application from being automatically shut down by the system.

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6. Battery and power problems

A worn-out battery is one of the most insidious reasons for Mi Band 4 shutdowns. When the battery degrades, it can’t provide stable power to the Bluetooth module, and the bracelet periodically drops out of the network.

Determine the wear of the battery can be according to the following signs:

The bracelet is turned off at a charge level of 30-50% (although it used to work up to 10%).

Charging occurs unevenly (for example, from 20% immediately jumps to 80%).

The bracelet warms up strongly during charging or use.

Another possible problem is poor charging contact, if the bracelet is undercharged, it may not work properly, and check if the charger contacts are not oxidizing or dirty (especially if the bracelet often sweats or gets wet).

• 🔋 Check the actual battery capacity with the Mi Band 4 Tools app (Battery Info tab). If the battery capacity is below 80 mAh (from the original 135 mAh), it is time to change the battery.
• 🔌 Clean the charging contacts with a cotton swab soaked in alcohol.
• 🔄 Try another charging cable - sometimes the problem is in the damaged wire.
• 🛠️ Replace the battery (cost) ~500-800 rubles in the service center).

⚠️ Warning: If the bracelet is swelling (the body has deformed), DO NOT try to charge or disassemble it yourself - this can lead to fire.

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7 Rare causes: from interference to factory marriage

If all of the above methods didn't work, the problem could be unique, and here are a few non-obvious reasons that few people know about:

Conflict with other smart devices, like if you have a Xiaomi smart bulb or socket at home, they can use the same Bluetooth channel as the bracelet. Try turning them off during the test.

— Problems with SIM-On some smartphones (especially Samsung and Huawei) SIM-The card can interfere with Bluetooth. Try temporarily removing it and check the stability of the connection.

In the 2019 Mi Band 4 batch, there was a defect in the soldered Bluetooth module contacts. If your bracelet is from this batch, it can be replaced for free under warranty (even if it expires - Xiaomi admitted the defect).

If you wear a bracelet next to a magnet (for example, in a case for a magnetically mounted phone), it can disrupt the compass and Bluetooth module.

• 📡 Change your Wi-Fi router channel to 5 GHz (if it runs at 2.4 GHz).
• 📶 Disable other Xiaomi smart devices during the test.
• 🔍 Check the serial number of the bracelet on the Xiaomi website – if it is from a defective batch, contact in support.
• 🧲 Remove magnets near the bracelet (cases, holders, bags with magnetic fasteners).

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8. Complete reset and reconnect the bracelet

If none of these methods worked, the last resort is to completely reset the bracelet to factory settings, which will delete all the data from the device, but often helps restore a stable connection.

Before reset, be sure to sync your data with Mi Fit so you don't lose your activity history, and write down your notification and alarm settings, which you'll have to reset once you reset.

If the bracelet still turns off after reset, try linking it to another phone to help determine if the bracelet or a problem in your smartphone is to blame.

Synchronize data with Mi Fit|Record the current settings|Prepare a second phone for the test|Make sure the bracelet is charged. >50%|Download the latest version of Mi Fit

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1. Open Mi Fit and go to Profile → Mi Band 4 → Disable the device.
2. On the bracelet, reset: press and hold the touch button for 20 seconds until the Mi logo appears.
3. Reconnect the bracelet via Mi Fit, following the instructions on the screen.
4. After connecting, do not restore data from the backup – set up the bracelet from scratch.

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If the bracelet is stable after reset, the problem was damaged settings or data conflict, in which case DO NOT restore the old settings from the backup - set it up again.

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FAQ: Frequent questions about connection issues