Are you trying to download a file, update an application, or simply open a website, but your smartphone persistently shows the error “No Internet connection” - although the mobile network seems to be working? Or does the data transfer turn on and off for no apparent reason? This problem is familiar to millions of users Android, and it can occur on both budget Xiaomi Redmiand flagships. In 80% of cases, software problems are to blame, but sometimes the root of evil lies deeper - in hardware failures or the actions of the mobile operator. Samsung Galaxy S24. In 80% of cases, software problems are to blame, but sometimes the root of evil lies deeper - in hardware failures or the actions of the mobile operator.

In this article we will look at why data transfer to all possible reasons, for which data transmission to Android does not work - from trivial errors in settings to complex system conflicts. You will learn how to diagnose a problem in 2 minutes, which parameters to check first, and when to take your phone to a service center. We also collected up-to-date data on the most vulnerable models (for example, why Realme 9 Pro the network often loses after updating to Android 14).

Spoiler: in 60% of cases, a simple reboot or network settings reset helps. But if you have already tried this, read on to find a solution for your specific case.

1. Problems with the SIM card: from oxidation of contacts to blocking by the operator

The first thing you need to check is the SIM card itself. Even if it looks normal outwardly, microcracks, contact oxidation or software blocking they can completely paralyze data transmission. This is especially true for devices with hybrid slots (for example Samsung Galaxy A54), where the SIM and memory card share one slot.

How to diagnose:

  • 🔍 Visual inspection: remove the SIM card and check the contacts for green deposits (oxidation) or scratches. If the card is bent, replace it.
  • 📱 Test in another phone: insert the SIM into another device. If the mobile data does not work there either, the problem is with the card or the operator.
  • 📡 Checking blocking: call the operator’s number (for example, *111# for MTS) and request the status of the “Data Transfer” service. Sometimes it turns off automatically when the balance is zero.

If the SIM card is OK, but data is not transferred, try force select network operator manually:

  1. Go to Settings → Mobile network → Telecom operators.
  2. Disable the "Automatic selection" option and select your operator manually.
  3. Restart your phone.
⚠️ Attention: if you use eSIM (for example, on Google Pixel 7 or iPhone 14), the problem may lie in incorrect profile activation. Remove and add the eSIM again through the operator's application.
📊 What mobile operator do you have?
MTS
Beeline
Megafon
Tele2
Yota
Other

2. Incorrect APN settings: why automatic configuration does not always work

APN (Access Point Name) is a “bridge” between your phone and the operator’s network. If the APN settings are incorrect or outdated, data transfer will not be possible, even if the network indicator is on. Most often this happens after:

  • 📱 Firmware updates (especially on Android 13/14).
  • 🔄 Factory reset.
  • 🌍 Roaming (for example, when traveling abroad).

How to fix:

  1. Open Settings → Mobile network → Access points (APN).
  2. Click on the three dots in the upper right corner and select “Reset to defaults.”
  3. If this does not help, create a new APN manually (parameters can be found on your operator's website).

Example of correct APN parameters for MTS (relevant for most regions in 2026):

Parameter Value
Name MTS
APN internet.mts.ru
User name mts
Password mts
Authentication type PAP
⚠️ Attention: some operators (for example, Tele2) use different APNs for 4G and 5G. If you have a smartphone that supports 5G (for example, OnePlus 11), make sure that the correct profile is selected.

Make sure mobile data is turned on

Check your balance (sometimes operators block the Internet at zero)

Download the current APN settings from the operator’s website (if there is such an option)

Reboot the phone after changes-->

3. Software failures: from cache to firmware conflicts

If data transfer was working normally, but suddenly stopped, it’s your fault software failure. This could be:

  • 🗑️ Clogged cache system applications (especially com.android.phone).
  • 🤖 Conflict after update (for example, on Android 14 many users POCO X5 complain about network loss).
  • 🛠️ Incorrect operation of Google Play services (especially if you use custom firmware like LineageOS).

Step-by-step solution:

  1. Clear cache: 
    Settings → Applications → Three dots → Show system → Find "Phone" and "Google Play Services" → Storage → Clear cache
  2. Reset network settings: 
    Settings → System → Reset → Reset Wi-Fi, mobile network and Bluetooth settings
    ⚠️ Attention: after this you will have to re-enter your Wi-Fi passwords!
  3. Safe Mode: boot the phone into safe mode (press and hold the button shutdown → long tap on “Turn off” → “Safe Mode”). If the Internet works in it, the third-party application is to blame.

If the problem appeared after updating the firmware, try roll back to the previous version (instructions for popular brands:

What to do if the network disappears after resetting the settings mobile communication?

If after the reset you have lost not only the Internet, but also your voice connection, check:

1. Is the SIM card inserted correctly (sometimes the slot may be damaged).

2. Is the “Voice Communication” service active at the operator (sometimes it is disabled). when resetting).

3. Is there any physical damage to the antenna module (for example, after dropping the phone).

If all else fails, contact a service center to diagnose the module RF (radio frequency).

4. Hardware faults: from the antenna to the motherboard

If all software methods have been tried, but data transfer still does not work, the problem is hardware. The most common reasons:

  • 📡 Damage to the antenna module (often after a fall or moisture).
  • 🔌 Faulty SIM slot (contacts come off or are oxidized).
  • 🔧 Problems with the motherboard (for example, burnt out RF chip after a power surge).

How diagnose:

  1. Signal check: enter the command in the engineering menu: 
    ##4636##

    Go to the “Phone Information” tab and look at the indicators Signal strength. If the value is lower -100 dBm , the antenna is not working well.

  2. Test in different places: if the network can be received in one room, but not in another, the problem may be in the operator's coverage area.
  3. Checking the heating: if the phone gets very hot in the upper part (where the antenna is located) - this is a sign of a malfunction RF module.

Critical moment: if after the phone falls not only data transmission, but also Wi-Fi/Bluetooth stops working - with a 95% probability the motherboard is damaged. In this case, repairs will cost 30-70% of the cost of the device.

Symptom Probable malfunction Repair cost (2026)
No network, but SIM card is detected Antenna module 1 500 — 3 000 ₽
The phone does not see the SIM card Damage to the SIM slot or contacts 1 000 — 2 500 ₽
Data transfer only works in 2G Faulty 4G/5G module 3 000 — 8 000 ₽ 
adb backup -apk -obb -shared -all -f backup.ab

This will save applications, their data and media files to the computer.-->

5. Conflicts with VPN, firewall or antivirus

Many users install VPN applications (for example, ProtonVPN or NordVPN) or firewalls (for example, (like NetGuard) to protect traffic. But sometimes these apps block mobile data completely, even when turned off. The following may also be to blame: VPN applications

  • 🛡️ Antiviruses (For example, Kaspersky or Avast), which restrict background traffic. data-i="188">Antiviruses
  • 🔒 Energy saving settingsthat disable mobile data for individual applications.
  • 🌐 Proxies, manually configured in Wi-Fi/mobile network settings.

How to fix:

  1. Open Settings → Applications and find VPN/firewall. Clear cache and data, then uninstall the app.
  2. Check Settings → Battery → Mode energy saving and disable mobile data limits.
  3. Reset the proxy settings: 
    Settings → Mobile network → Advanced → Proxy (should be "No")

If you use Android 12+check Mobile data permissions:

  1. Go to Settings → Applications → Three dots → Special access → Unrestricted data access.
  2. Make sure that the applications you need (for example, Chrome or YouTube) are not limited.
⚠️ Attention: some banking applications (for example, SberBank Online or Tinkoff) block operation when the VPN is active. If payment services do not load for you, temporarily disable the VPN.

6. Problems on the operator's side: from technical work to IMEI blocking

Sometimes it is not the phone that is to blame, but mobile operator. Here are the most common scenarios:

  • 🔧 Technical work operator-based (usually lasts 1-3 hours).
  • 📵 IMEI blocking (if the phone is blacklisted as lost/stolen).
  • 📉 Exhausting the traffic limit (even if you have “unlimited”, operators often throttle the speed after 50-100 GB).
  • 🌍 Roaming errors (for example, when traveling to a region with a different network standard).

How to check:

  1. Call the operator's hotline (numbers:
    • MTS: 0890
    • Beeline: 0611
    • Megafon: 0500
    • Tele2: 611
  • Check the IMEI status on the website imei.info (if the phone is locked, unlocking will cost 500-2,000 ₽).
  • Send USSD request to check the balance and limits: 
    *100# (MTS), *102# (Beeline), *105# (Megafon), *155# (Tele2)

    • If the operator has confirmed the problems on its side, you can only wait. But if the blocking is related to IMEI, you need to wait. you will have to:

    • Contact the communication salon with documents on your phone (if the blocking is erroneous).
    • Use the services of unlocking services (for example, IMEI-Unlock), but this is semi-legal and can lead to repeated blocking.
    💡

    If the operator claims that everything is in order on his part, but the problem persists, demand a written response with diagnostics. This will be useful for warranty repairs of the phone.

    7. Features of specific models and firmware

    Some smartphones have unique bugsrelated to data transfer. Here are the most problematic models for 2026:

    Model Problem Solution
    Samsung Galaxy S22/S23 (Exynos) 5G disappears after upgrading to One UI 6.0 Roll back the firmware or reset the network settings
    Xiaomi Redmi Note 12 Mobile data is disabled when connected to Wi-Fi Disable the "Auto switch to mobile data" option
    Realme 9 Pro No Internet while roaming Manually select the operator's network
    Google Pixel 7/8 Conflict with eSIM with dual SIM card Remove and add eSIM again

    If you have one of these models, first try proprietary solutions often helps. For devices on from the manufacturer. For example, for Samsung installation of the latest security patch through Smart Switch.

    For devices on MediaTek (for example, POCO X5 or Infinix Note 30) can required manual configuration of the network mode:

    1. Go to Settings → Mobile network → Network type.
    2. Select LTE only (if necessary Auto or 5G/LTE/3G).
    3. Restart the phone.

    8. Alternative diagnostic methods and solutions

    If standard methods did not help, try advanced diagnostic methods:

    • 📊 Network logs: use the application NetMonster or Network Signal Infoto analyze connection parameters (for example, RSRP and SINR).
    • 🔧 ADB commands to reset settings modem: 
      adb shell

      su
      

      setprop ril.radio.sglte 1
      

      reboot

      ⚠️ Attention: these commands require root access and can lead to loss of connection if entered incorrectly!
    • 📱 Test in the engineering menu: enter #0011# (for Samsung) or ##4636##* (for most Android) to check the status of the radio module.

    If you are sure that the problem is in the firmware, but rolling back does not help, consider flashing via FastbootFor example, for Xiaomi:

    1. Download the official firmware from site Xiaomi.
    2. Unzip the file and run flash_all.bat in Fastboot.
    3. Wait for completion (the phone will reboot automatically).

    For Samsung a similar procedure is performed through Odin using files BL, AP, CP, CSC.

    💡

    If you decide to reflash the phone yourself, be sure to check the model number IMEI on the manufacturer's website. Installing firmware from a different modification (for example, for Redmi Note 12 Pro instead of Redmi Note 12 Pro+) can turn the device into "brick".

    FAQ: Frequently asked questions about data transfer on Android

    mobile data works, but very slowly. What's wrong?

    Most likely, the operator is throttling the speed. Check:

    • The remaining traffic according to the tariff (sometimes). “unlimited” is actually limited to 50-100 GB).
    • APN settings (sometimes operators change the settings for high-speed access).
    • Network mode (if it is 3G, switch to LTE or 5G).

    Also try turning off the VPN and checking the speed at website Speedtest.

    After updating Android, mobile data stopped working. What should I do?

    This is a typical problem for Samsung, Xiaomi i Realme. Try:

    1. Reset network settings (Settings → System → Reset → Reset mobile network).
    2. Delete and re-add APN.
    3. Roll back to the previous firmware version (if there is a backup).

    If nothing helps, write to the manufacturer’s support with indicating the model and firmware version.

    The phone shows that mobile data is turned on, but the Internet does not work. Why?

    Probable reasons:

    • The SIM card is not activated for data transfer (check with your operator).
    • On the phone enabled Modem mode or Access point, which blocks Internet access for the device itself.
    • Antivirus or firewall blocks traffic (check the settings Avast, Kaspersky or NetGuard).
    Is it possible to repair the antenna yourself?

    Theoretically yes, but:

    • This requires soldering iron, multimeter and experience in working with microelectronics.
    • On modern smartphones, the antenna is often integrated into the screen or middle frame - replacing it without damaging other components is almost impossible.
    • The cost of self-repair (including the purchase of spare parts) often exceeds the price of a service at a service center.

    If you still decide, look for disassembly of your model on YouTube (for example, "Samsung Galaxy A54 disassembly") and order spare parts only from trusted sellers (for example, on AliExpress from official stores like HQ Cellphone Parts Store).

    How to check if the operator is blocking my IMEI?

    Checking methods:

    1. Enter on your phone *#06# - yours will appear IMEI.
    2. Check it on the sites:
  • If the status is "Blacklisted" - contact the communication store with documents for the phone.

    • If the phone was purchased second-hand, check it on the website sndeep.info - there you can see the history of blocking and linking to operators.