The situation when on the screen of the smartphone Xiaomi suddenly appears the inscription “No network” or “No” SIM-It can take you by surprise at the most inopportune moment, and it's not just losing your Internet access, it's also risking missing a critical call or message. Users often start to panic, assuming the breakdown of expensive equipment, but in most cases the problem lies in software failures or incorrect settings of the mobile operator.
Modern Xiaomi smartphones, which are based on the shell MIUI or HyperOS, have a complex architecture of radio modules that can conflict with base station updates or local firmware failures. Before carrying the device to the service center, you need to conduct a thorough diagnosis, eliminating trivial causes such as contamination of contacts or temporary failure of registration in the network. In this article, we will discuss in detail the algorithms of actions that will help return a stable cellular signal without contacting the masters.
It is worth noting that the lack of signal can be caused by both physical damage to the antenna and software conflict that arose after a failed system update. Xiaomi regularly releases security patches that sometimes incorrectly interact with modem drivers. So if your phone stopped seeing the network, the first thing to do is to analyze what changes preceded the problem.
Primary diagnosis and verification SIM-map
The first step in solving the problem should be to eliminate the physical defect of the operator's card. SIM-They're oxidized or contaminated, which prevents normal communication with the phone. Remove the tray, gently wipe the chip with a soft dry cloth and set it back, making sure it's flat and not wobbling. If you have the opportunity, insert your own. SIM-card to another phone to make sure it is serviceable and active.
It is important to check whether the tray itself is damaged. SIM-In hybrid slot devices, make sure the card is installed in the correct slot, intended for the main modem, and not for the second card or memory card. Mechanical damage to the contacts SIM-Cards are one of the most common causes of network loss.
⚠️ Warning: Never use metal objects to clean your contacts SIM-Also avoid using liquids other than isopropyl alcohol and only in minimal amounts.
If you are using a very old one SIM-A card issued many years ago may not be compatible with modern communication standards. 4G/LTE. In this case, the operator can block the connection, and the only solution is to replace the card with a new one in the communication room.
- 📱 Remove and re-install. SIM-map, checking the density of the fitting.
- 🔄 Try inserting the card into another slot (SIM 1 SIM 2) because one of the modules may not work properly.
- 🧹 Clear the contacts. SIM-maps and trays from dust and oxidation with dry napkin.
After you manipulate the card, be sure to restart the device. The system should re-interview the slot status and try to log in to the network. If after the reboot the link indicator appeared but quickly disappeared again, the problem may lie deeper in the network settings or software.
Network settings and operator selection
Often the reason for the lack of a signal lies in the wrong mode of operation of the network. 4G where the coverage is weak, ignoring the stable 3G or 2G. To correct the situation, you need to go to the settings menu and force the network type to change. → SIM-maps and mobile networks → Network type and select preferred option, such as "Preferred" LTE» or "Only" 3G» check out.
Another effective method is manually selecting a carrier. Auto mode sometimes makes mistakes when switching between towers of different frequencies. Go to the operator's selection menu, turn off automatic search and wait for the list of available networks to appear. Choose your carrier from the list; if the phone is successfully registered, then the problem was in the automatic switching algorithm.
In some cases, resetting your network settings to factory values helps. This action will not delete your personal data, photos or contacts, but will return all Bluetooth, Wi-Fi and mobile network settings to their original state. The path to this feature is usually in Settings → Connection and Sharing → Reset Wi-Fi, mobile networks and Bluetooth.
| Setup parameter | Recommended value | When to apply |
|---|---|---|
| Type of network | LTE is preferred | For standard use in the city |
| Choice of operator | Manually. | When switching or “no network” |
| Data roaming | Included (if abroad) | When you are outside the home regional area |
| Flight mode | Off. | Basic status for communication |
Remember that after changing the network settings, it can take your phone 30 seconds to 2 minutes to re-register at the base station.
Verification and Configuring of APN Access Points
Access points (APN) — These are the gateways through which your phone connects to the carrier's Internet, and if those settings are lost or deleted, the phone may show that the network is there, but the Internet will not work, or the connection may be completely absent. → SIM-maps and mobile networks → (Choose. SIM) → Access points (APN).
In the access point menu, you should see a configuration list. If the list is empty or the current point is inactive, you need to create a new one. APN» or "Reset to default settings." The correct settings for your region and operator can be found on the official website of the provider or get by sending a special service. USSD-code.
Where to find the exact APN settings for your carrier?
The APN type field should be carefully considered, and should contain default, supl, or default. If it has other values or the field is empty, the Internet will not work. After making changes, make sure to save your profile and select it as active by ticking or radio buttoning.
- 🌐 Go to the access point menu (APN) mobile network settings.
- 🗑️ Click the menu (three dots) and select Reset to default settings».
- ✅ Make sure the new access point is active (green dot or tick burning).
If automatic resets don’t work, create a new hotspot manually by entering data from the operator. Sometimes old, accumulated APN profiles conflict with new standards for encrypting traffic, so removing unnecessary profiles can be a crucial factor.
Resetting settings and restarting the radio module
When simple methods don't work, you need to get more in-depth. Network resets, which I mentioned earlier, often solve the problem, but if that doesn't work, try forcing the radio module to restart via an engineering menu or special codes. Type ##4636### in the phone book (number dialer).
You'll see a hidden test menu. Select Phone Information. Here you'll see the status of the connection and the mode switching option. Try pressing Turn off radio, wait 10 seconds, and then Turn on radio, which force you to restart the communication module, bypassing the standard system reboot.
☑️ Actions in case of failure of the radio module
In the same menu, look for the option "Install preferred network type" and try changing it to another one, such as LTE Only to GSM Only, and then return it back, which causes the modem to re-enter the network without cached errors.
⚠️ Warning: Be careful in the engineering menu.Do not change the values that are not sure, especially those related to frequencies (Band), as this can lead to the complete disappearance of the signal until the next reset settings.
After manipulating the radio module, it is recommended to perform a full reboot of the smartphone, which will allow the system to correctly initialize all hardware drivers, taking into account the changes made. If after the reboot the signal appeared but quickly disappeared, it is possible that the problem is hardware in nature or is associated with overheating of the modem.
Impact of MIUI updates and reset to factory
Updates to the MIUI/HyperOS operating system often contain bug fixes, but sometimes bugs that disrupt communication. If the problem occurs immediately after the update, you should look for information about such cases on the user forums of your model. In some cases, waiting for the next patch helps, but most often you need to reset.
A radical but effective method is a complete factory reset (Hard Reset).Be sure to back up all important data before doing so, as this procedure will completely remove information from the device's internal memory. Go to Settings → About Phone → Reset → Clear all data.
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A complete reset eliminates software conflicts, but requires prior data backup.
When you reset, the phone will go back out of the box. Don't restore all the applications from the backup at once, but first check the network on the clean system. If the signal is stable, then some third-party application or setting conflict caused the problem. Install the programs gradually, tracking the modem response.
Even if the signal is missing or permanently disappears on a clean firmware without installed applications, the probability of a software error decreases and the probability of a hardware malfunction increases, in which case further manipulation of the software part may be useless.
Hardware problems and modem diagnostics
When all software methods are exhausted, it remains to consider a physical breakdown, which can be the departure of the antenna plume, the oxidation of the contacts on the motherboard or the failure of the radio module itself, often after falls, moisture or prolonged overheating of the device.
Notice how the phone behaves: Is the lower body (where the modem is usually located) overheating? Is the battery running out faster than usual? These signs may indicate short circuit or antenna path failure. At home, hardware diagnostics are limited, but visual inspection and careful disassembly (if skillful) can reveal obvious defects.
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If the phone fell, even from a low altitude, the antenna connector could move away, and a careful press on the back cover in the area of the antenna inserts sometimes temporarily restores contact.
Some Xiaomi models have a known defect in the modem dump, where the chip is soldered off the board due to thermal expansion when heated. This is a complex malfunction requiring professional repair using a soldering station and a microscope. Self-repair in this case is not recommended, since there is a high risk of permanently damaging the board.
- 🔍 Inspect the antenna connectors inside the housing for oxidation or retreat.
- 🌡️ Monitor the temperature of the body in the lower speaker area when trying to connect to the network.
- 🔧 Check the integrity of the antenna contacts on the device frame (if they are displayed on the body).
If you don’t have the skills to repair electronics, the best solution is to contact an authorized service center, specialists will conduct diagnostics on special equipment and tell you exactly whether your Xiaomi is recoverable or if you need a replacement board.