The problem of an unstable Internet connection or periodic disappearance of the network is familiar to many smartphone owners, especially devices running on the shell of MIUI or the new HyperOS. Users often complain that in the zone of confident reception of their Xiaomi suddenly switches to EDGE or completely loses communication, turning into a useless piece of plastic.
The reasons for this behavior can range from simple software failures after a system upgrade to physical damage to an antenna module. Sometimes it is a specific energy saving setting that aggressively shuts down the radio module to save charge, and understanding the source of the problem is the first step to solving it.
In this article, we'll take a comprehensive approach to restore connectivity: you'll learn how to use hidden engineering menus correctly, what network settings to manually change, and when to bring a device to a service center. Some techniques require care, but they can actually work wonders.
Diagnostics and analysis of the current signal level
Before you start to take action, you need to objectively assess the situation. Standard "rods" in the corner of the screen are often misleading, because they show an average value. For accurate diagnosis, it is better to use numerical indicators of the signal level in decibels (dBm).
To see the real picture, go to Settings. → The phone. → All specs → Status SIM-Here you're interested in signal strength. -50 before -80 dBm is considered a great signal. If you see the numbers below -100 dBm (e.g, -115), The communication problems are understandable.
⚠️ Note: If the signal level is constantly lower -120 dBm even outdoors, this may indicate a faulty antenna plume or oxidation of the module contacts.
It’s also worth checking which communication standard the phone runs on. Modern devices often try to “cling” to 4G/5G where the signal is weak, instead of operating stably in 3G. Forced switching can significantly improve the quality of voice communication.
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To quickly check the signal level without logging into the menu, use USSD-##4636###. Select "Phone Information" for detailed statistics.
Basic software settings of the network
The simplest and often ignored method is to fine-tune network priorities: telecom operators are gradually turning off old 2G/3G towers, but phone algorithms may be trying to find them. Forced installation of a preferred type of network often solves the problem of the “jumping” Internet.
Go to Settings. → SIM-Select your primary SIM card and find Preferred Network Type. LTE", Try changing it to "Only" LTE" or "Only." 3G" It's not going to be a constant search for a better network.
- 📱 Make sure that VoLTE (Voice over) is enabled LTE), If your operator supports it, it will improve the quality of voice communication through the 4G.
- 🔄 Try to manually select a carrier instead of automatic mode, sometimes the phone clings to the roaming partner.
- 🔋 Turn off the power saving mode for check, as it may limit the operation of the radio module.
And don't forget to reset your network settings, and it won't delete your personal data, but it will return all the connection settings to factory values. → Connection and sharing → Reset Wi-Fi, mobile networks and Bluetooth.
☑️ Checklist of basic settings
Use of engineering menus and hidden codes
For advanced users, the MIUI shell provides access to hidden radio functions, which is called an engineering menu that allows you to fine-tune the parameters of the signal reception. Be careful: changing unknown parameters can lead to malfunctioning of the phone.
Dial the code ##4636##. If the menu opens, select Phone Information. You can find the option "Install preferred network type" here. For most regions, LTE Only (4G only) or LTE/TD-SCDMA/WCDMA are relevant.
⚠️ Attention: When choosing a regime "LTE Only" you may lose the ability to receive incoming calls if the operator does not support VoLTE technology.
Another useful code for Xiaomi devices is ##6484##. This is the hardware testing menu (CIT). Here's where you can run a test. SIM-If the test shows an error, it's likely that the problem is hardware.
What do I do if the codes don't work?
Work with SIM-map and physical components
Often the root of evil is not software, but physical contact. SIM-Cards issued more than 5 years ago may not work properly with current standards. 4G+. The contacts may also have been oxidized or contaminated.
Carefully remove the tray SIM-Wipe the map with a soft dry cloth. Notice the tray, it has to sit tightly in the case. If the tray is hanging, it can interfere with the tightness and contact with antenna plumes located next to it.
If you have a two-sim phone, try changing it. SIM-Sometimes the second slot has less bandwidth or only works in mode. 2G/3G, Which causes speed problems.
| Symptoms. | Possible cause | Decision |
|---|---|---|
| The network disappears when you touch the phone | Poor SIM or antenna contact | Transform SIM, check the tray |
| Only 2G/Edge | Old one. SIM-map | Replace the SIM with the operator |
| No net after the fall | Removal of the antenna connector | Disassembly and reconnection of the plume |
| "No access to SIM" | Oxidation of contacts | Cleaning contacts with a swallow |
Impact of system updates and resetting settings
After major MIUI or HyperOS updates, users often notice a deterioration in communication, because new network configuration files may conflict with the current operator profile, in which case a complete reset of network settings helps.
If a simple reset didn't work, you can try a more radical method, which is to reset all settings to factory settings. Importantly, make sure you back up all the important data before you do that, because the phone will go back out of the box.
Sometimes the problem lies in the cache of Google system services or the interface itself, and cleaning the cache of the Phone and Settings app can remove software errors that prevent you from registering correctly on the network.
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If the problems started immediately after the firmware update, most often it helps to wait for a patch from Xiaomi or roll back on the previous stable version.
Hardware problems and external factors
And don't discount the externalities: metal cases, magnetic holders in the car, and even thick glass in new buildings can shield the signal. Try removing the case and checking the signal level.
If the phone fell or fell into the water, the main antenna connector could move away. In Xiaomi smartphones, antennas are often located around the perimeter of the body or integrated into the back cover. Any crack in the body can disrupt the antenna circuit.
- 🏗️ In basements and elevators, communication loss is normal due to shielding of concrete and metal.
- 📱 Thick protective glasses with metallized frames can reduce the signal level on the 10-15%.
- 🔋 A bloated battery can physically press on antenna plumes, disrupting contact.
In case of physical damage, only a visit to the service center will help, the masters will check the integrity of the antenna module and, if necessary, replace the plume or the radio module itself.