The “E” icon instead of 4G, constant network search or complete loss of signal on an Android smartphone often blocks the ability to make an important call, and the reason may lie either in a network settings failure or in a physical malfunction of the antenna.
Before you panic and If you take your gadget to a service center, you should carry out a number of independent checks. Often the cause of the failure is a temporary modem glitch, an incorrectly selected SIM card, or the characteristics of the area where you are located. We have compiled a detailed guide that will help you get a stable signal back without wasting time and money. If simple methods do not help, you will learn how to diagnose more serious problems.
Primary diagnostics and basic actions
The very first step in case of any communication problems is to eliminate temporary failures in the operation of the radio module. The operating system Android occasionally freezes when switching between cell towers, especially if you were moving at high speed. Simply rebooting the device causes all system services, including communication services, to be reinitialized, which often solves the problem instantly.
If rebooting doesn't work, try putting the phone in airplane mode. Turn on Airplane mode for 10-15 seconds and then turn it off. This action forcibly breaks the connection to the current base station and forces the phone to search for the nearest available tower with the strongest signal. This method works faster than a full reboot and is an effective way to “shake up” network settings.
It is also worth checking if you have the power saving mode turned on. Some smartphone manufacturers, such as Samsung or Xiaomi, in aggressive battery saving modes can limit the operation of background network search processes. Disable power saving mode and check the signal strength. If it is restored, then the problem was in the battery optimization settings.
If you are in a basement or building with thick walls, try going to a window. The 4G/LTE signal does not penetrate well through reinforced concrete and metal structures, so physical movement often solves the problem instantly.
Checking the SIM card and slot
One of the most common reasons for poor reception is physical wear or contamination of the SIM card. Over time, the contacts on the chip can oxidize or become covered in dust, impairing data transfer between the card and the phone. Carefully remove the tray using a paper clip, wipe the contacts of the SIM card with a soft, dry cloth or eraser (very carefully) and insert it back, making sure it fits tightly.
If you have a dual-SIM phone, try moving the card to a different slot. Sometimes one of the slots may be unstable due to a manufacturing defect or moisture. Also, check the card format: old large SIM cards cut with nano-SIM scissors may have damaged contacts or incorrect thickness, resulting in poor contact.
- 📱 Try installing your SIM card in another phone to see if the problem is in the card or in the smartphone itself.
- 🔧 Inspect the SIM card tray for deformation or oxidation of contacts inside the phone.
- 🔄 If the card is very old (issued more than 5-7 years ago), contact the operator's salon for a free replacement with a new one with 4G support.
It is important to consider the age of the SIM card itself. Carriers are constantly upgrading their networks, and older cards may not work correctly with new encryption standards and frequencies. Replacing the card with a new one in the operator’s office often solves the problem of a “floating” signal without any additional phone settings.
☑️ SIM card diagnostics
Setting the network type and preferred mode
Modern smartphones are by default configured to automatically select the network type (5G/4G/3G/2G). However, in areas of poor reception, the phone can constantly “throw” between standards, trying to find the best signal, which ultimately leads to its complete absence. In such cases, it is advisable to manually record the network type. Go to Settings → Connections → Mobile networks → Network mode and select Force Only 4G (LTE) or Only 3G.
Fixation on 3G is often a salvation in rural areas or outside the city, where 4G coverage is only spotty, and 3G works more stable and has a greater range from the tower. Although the Internet speed will be lower, voice communication will become much more stable. This is a compromise that allows you to stay connected where the automatic mode does not cope well.
⚠️ Attention: Forcing the “4G Only” mode on some phone models may result in incoming calls not going through if the operator does not support the technology VoLTE (Voice over LTE). In this case, return the setting to automatic mode or select “3G/2G.”
For more advanced users, there is a hidden service menu, accessible by dialing a special code. By entering ##4636## in the Phone application, you will be taken to the testing menu. Here in the section Information about the phone You can select a specific preferred network type from the extended list. Be careful: incorrect settings in this menu may temporarily disable the radio interface of the device.
Codes for entering the engineering menu
For most phones on MediaTek chips, the code works ##3646633##, and for Qualcomm processors it is often used ##4636##. However, on new versions of Android, access to these menus may be blocked by the manufacturer.
Resetting network settings to factory settings
If manipulating the SIM card and selecting the network mode did not help, the system may have accumulated errors in the configuration of access points (APN) or network protocols. In this case, the solution would be to reset the network settings. This procedure will not delete your personal data, photos or applications, but will return Wi-Fi, Bluetooth and mobile settings to factory settings.
To perform a reset, follow the path Settings → System → Reset settings → Reset Wi-Fi, mobile data and Bluetooth settings. On different shells (MIUI, OneUI, ColorOS), the path may differ slightly, but the essence remains the same. After confirming the action, the phone will reboot, and you will have to re-enter passwords for Wi-Fi networks and pair with Bluetooth devices.
| Action | What is being reset | What is saved |
|---|---|---|
| Reset network settings | Wi-Fi passwords, APN settings, paired Bluetooth devices | Photos, contacts, applications, messages |
| Reset all settings | Everything, including accounts and application data | Only system files (data is deleted) |
| Hard Reset | Full memory clear to factory state | Nothing (backup required) |
After resetting the network settings, the phone will begin registering on the network as a new device. This often allows you to resolve conflicts that arise after updating the firmware or changing the telecom operator. If the problem was caused by incorrect access point parameters, they will be restored automatically the first time you try to access the Internet.
Software and firmware updates
Smartphone developers regularly release security and system updates, which often contain fixes for radio module errors. If your phone has poor network reception after a recent update, there may be a bug in the new version. However, most often the situation is the opposite: installing the current version improves connection stability. Check for updates in the section. If the manufacturer has released new firmware, be sure to install it. In the description of updates (release notes) they sometimes directly indicate: “Improved mobile network stability” or “Fixed problems with connecting to LTE.” Ignoring these updates may leave you with an unfixed software glitch. Android improves connection stability.
Check for updates in the section Settings → About phone → System update. If the manufacturer has released new firmware, be sure to install it. In the description of updates (release notes) they sometimes directly indicate: “Improved mobile network stability” or “Fixed problems with connecting to LTE.” Ignoring these updates could leave you with an unfixed software glitch.
⚠️ Warning: Before updating the firmware, make sure your battery has at least 50-60% charge. Interrupting the update process due to a low battery can lead to the device becoming bricked, after which the phone will no longer turn on at all.
In rare cases, the problem may be specific to a particular firmware version from the manufacturer. If the update did not help, and the problem appeared recently, you can try searching the forums to see if other users of your model are complaining about similar problems. Sometimes rolling back to a previous version of the software helps, but this is a complex procedure that requires unlocking the bootloader.
Hardware problems and external factors
When all software methods have been exhausted, it is worth thinking about the physical reasons. Antennas in modern smartphones are located around the perimeter of the case, often in plastic frame inserts. If the phone was dropped, the antenna cable could come off the motherboard or the module itself could be damaged. Even a microcrack in the housing can break the seal and oxidize the antenna contacts.
External accessories also affect the signal quality. Metal bumpers, cases with magnetic clasps, or thick protective glass with a metallic coating can shield the signal. Try removing the case and checking the connection level. If the signal has improved, then the accessory is an interference, and it should be replaced with a more “transparent” option for radio waves.
- 📉 Check whether the signal has deteriorated only in one specific location (home, office). There may be a problem in the operator's coverage area.
- 🛠 Inspect the case for signs of falling or moisture that could damage the internal components.
- 🧲 Remove magnetic phone holders in the car, they can interfere with the operation of the antenna.
If you suspect a hardware failure, do it yourself It is not recommended to open the phone, especially if it is under warranty. Unprofessional intervention may damage the moisture protection or other components. It is better to contact an authorized service center to diagnose the antenna path and replace the communication module if necessary.
If the phone has poor network reception only in certain places, but works perfectly in others, the problem is most likely in the coverage of the operator, and not in a malfunction of the smartphone.
Frequently asked questions (FAQ)
Why does the phone show 4G, but the Internet does not work?
This may mean that the phone is connected to the tower, but there is no data transmission. Check your account balance, make sure you haven't reached your data limit, and double-check your access point (APN) settings. Sometimes switching to airplane mode helps.
Does the new version of Android affect the signal?
Yes, updates can either improve or worsen reception. New versions of modem drivers often optimize network performance, but sometimes new features (such as constantly searching for 5G) can drain the battery faster and create the illusion of a poor signal.
Can a virus cause connection problems?
In theory, malware can overload the processor or block network services, but in practice this is rare. More often than not, the problem lies in the settings or hardware. Check your phone with an antivirus if you suspect an infection.
What is VoLTE and how does it relate to call quality?
VoLTE allows you to transmit voice over a 4G network, providing high quality sound and fast dialing. If this feature is disabled or not supported by the operator in your region, the phone will switch to 3G/2G during a call, which may be perceived as a loss of network.