The situation of a Xiaomi smartphone suddenly losing network or showing one or two sticks instead of a confident 4G, is familiar to many users. It is not just an annoyance, but a real problem that interferes with work, communication and navigation. Especially frustrating when you are in an area where neighbors or colleagues with other devices communicate consistently. owners of smartphones Redmi and Poco often face this because of the features of the firmware MIUI or HyperOS, which aggressively save energy, sometimes at the expense of communication quality.
In this article, we'll take a comprehensive approach to solving the problem of weak signal, and we'll go beyond the banal advice of "reset the phone," and delve into the technical settings of the modem, the engineering menu and the physical factors of influence. Understanding how the radio module of your device works will allow you to independently diagnose the cause of the failure and fix them without going to the service center.
Before we get into the complex manipulations, it's worth noting that the quality of communication depends on many variables, from the distance to the operator's base station to the material of the walls in your building. But software optimization of the Android shell is often a key factor. Forced fixation of the 4G/LTE network in the developer menu often solves the "jumps" between 3G and 4G that create the illusion of bad reception. Let's take a look at all the methods from simple to complex.
Basic diagnostics and physical inspection of the device
The first step should always be to check the physical condition of the device and the SIM card. Often the problem is not software failures, but in the banal oxidation of contacts or damage to the operator's card. Remove the SIM tray and carefully examine the chip. If you see scratches, darkening or contamination on the golden contacts, gently wipe them with soft cloth, not villous, or erased. Do not use alcohol or aggressive chemicals, as this can damage the protective coating.
Notice the case. Metallic, thick rubber or magnetic-clasp cases can shield the antenna. The antennas in modern smartphones are located around the perimeter of the case, and any foreign materials in the vicinity can reduce the sensitivity of reception by 20-30%. Remove the case and check the signal level. If the performance improves, the problem is solved by replacing the accessory.
⚠️ Attention: If yours SIM-map used more frequently 3-4 Older Mini-SIM cards, trimmed with Nano, often work unstablely.
It's also worth checking if the device is overheating. At high temperatures, the processor and modem can reduce their performance to protect components, which directly affects the power of the transmitter. If the phone is hot to the touch, let it cool before conducting communication tests.
Network setting and preferred connection type
Modern mobile networks are a complex mix of standards: 2G, 3G, 4G and 5G. Automatic switching between them, which is set by default, does not always work correctly in unstable coverage. A smartphone can “cling” to a weak 4G signal, instead of switching to stable 3G, or constantly searching for a 5G network, consuming charge and losing data packets.
For forced network type settings, go to the Settings menu → SIM-Select your SIM card and find Preferred Network Type. Here you will see options like "Preferred". LTE" or "Only." 3G". Selection of the regime “Only” LTE" (or 4G) It often helps to lock in a connection if you're at the edge of coverage, where the phone is constantly tossed between standards. However, remember that incoming calls may not pass if the operator does not support VoLTE technology.
📊 What type of network do you most often have?
4G/LTE
3G/H+
2G/E
5G
No signal.
Enable the VoLTE (Voice over) function LTE), If it's available to your carrier, it's a technology that allows voice to be transmitted as a data stream through the network. 4G, This is a huge improvement in sound quality and connection speed, and it's activated in the settings menu, which is usually the same place. SIM-Maps, switch Use VoLTE.
If you live in a zone where 4G It is very bad, but it is very confident. 3G, It is important to switch the phone to “preferably” mode. 3G". This is the speed of the Internet, but will provide stable voice communication. To return to automatic mode, just select the "Preferred" option. 4G/LTE".
The Android operating system, which runs the MIUI and HyperOS shells, has a hidden engineering menu designed to test hardware by engineers, but also available to ordinary users, and can allow a deeper calibration of the radio module to detect real signal performance digitally, rather than as conventional sticks.
To enter the testing menu, open the Phone app and dial ##4636##. If the code doesn't work, your firmware version may be blocking that access, so you can try the ##3646633## (on MediaTek processors) or install the MTK Engineering Mode app from the Play Market store.
After you log in, select Test → Phone Information. Here you are interested in Set Preferred Network Type. From the dropdown, you can select more specific modems, such as LTE Only (LTE only). Be careful: by choosing this mode, you may lose the ability to make regular voice calls if you do not have VoLTE.
What to do if the engineering menu code doesn’t work?
On new versions of Android and firmware MIUI The engineering menu is often closed, and you can use the Force app. LTE Only (4G/5G/3G/2G)" It creates a shortcut to the hidden system menu of network settings, allowing you to change modem modems without root rights.> And you can see in the same menu the decibel-milliwatts (dBm) parameter, which is the actual power of the signal, and the closer it gets to zero, the better the signal, -75 dBm is a great signal, -95 dBm is medium, and -110 dBm and below: a zone of insecure or no reception, and monitoring this indicator will help you find the best coverage in your apartment or office, reset your network settings and update your configuration. APN Accumulation of errors in network connection configuration is a common cause of communication problems. Over time, incorrect base station data or old access point settings may remain in the phone’s memory (APN). Resetting these settings returns the communication module to factory settings, eliminating software conflicts. To perform the reset, go to Settings. → Connection and sharing → Reset Wi-Fi, mobile networks and Bluetooth. Press Reset at the bottom of the screen. The system will warn you that stored Wi-Fi passwords and other Bluetooth devices will be deleted. This is a necessary sacrifice to restore the modem. ☑️ Checklist before reset Remember passwords from important Wi-Fi networks Make sure that the SIM card is active Charge the phone to a minimum 40%Record the current settings APN (If there are specifics, then the reset is completed: 0 / 5 After restarting the phone, re-enter the Wi-Fi password and check the mobile network. If the problem was a software configuration failure, the communication should stabilize (APN). Go to Settings. → SIM-maps and mobile networks → Access points (APN). Make sure your operator's access point is selected. If the list is empty or the settings are down, click the menu (three dots) and select Reset to Default. In some cases, operators send automatic settings via SMS. Make sure that these messages are not blocked by spam filters, or request that they be resent through the operator's personal account. Comparison of operators and frequency selection Not all operators cover the area equally well. Moreover, different operators use different frequency bands. Your Xiaomi phone supports multiple bands, but in a particular area, one frequency can break through walls better than another. For example, low frequencies (800 MHz, Band 20) penetrate buildings better but have lower capacity, and high frequencies (2600 MHz, Band 7) give high speed but do not break through obstacles. The table below compares the main characteristics of frequency bands used in Russia and the CIS. Understanding this will help you choose the operator or set the phone to the desired frequency (if such an option is available in the engineering menu). Band Frequency (MHz) Characteristics Ideal for Band 20 800 High penetration capacity of basements, countryside, buildings with thick Band walls 3 1800 Balance of coverage and speed of Urban development, suburbs of Band 7 2600 High speed, low coverage of Open Spaces, stadiums, and Band city centers 31 450 A huge cover (SkyLink/MTS) Remote villages, trails, forests If you're in an unsuspecting reception zone, try manually selecting an operator. Go to Settings → SIM-maps and mobile networks → Network and turn off automatic selection. Phone will scan the airwaves and show the list of available operators. Sometimes manual selection of "native" operator helps to fix the connection, which automatically breaks down. MIUI New HyperOS often contains modem driver updates. However, the opposite happens: after the system update, users begin to complain about the loss of communication. This can be due to bugs in the new version or changes in regional settings. In Xiaomi phones, the region affects the available frequencies and radiation power (due to legal restrictions of different countries). Try to change the region of the device. Go to Settings → Additional settings → Region. If you have "China" or an exotic country, change to "Russia", "Ukraine", "Kazakhstan" or "Germany". Changing the region to European (for example, Germany or France) often unlock additional frequencies (in particular, go to Setting the Settings, for the critical data, "Econs" also for the city, which are not responsible for the "Energy" or the "Energy" for the "Energy" or the "Energy" Although system processes are rarely restricted, third-party launchers or optimizers can interfere with network operation. Turn off Flight mode for 10 seconds, even if it is turned off, to force the phone to re-register on the network. ⚠️ Warning: Changing the region to China or India could lead to ads in system applications and changes in the set of pre-installed software (FAQ) Why is Xiaomi weak compared to iPhone or Samsung? This is a common observation, but not always true. The difference often lies in the modems used. Xiaomi often uses Qualcomm Snapdragon or MediaTek chips, which can work differently with specific carrier frequencies. In addition, the switching algorithms between towers in MIUI They may be less optimized for LANs than Android or iOS.Region change and fixation LTE Does sticking foil on a SIM card help? No, it's a dangerous myth. SIM-The card can lead to short circuit and failure of the reader SIM The only modding that's allowed is to clean the contacts with a smooth sweep if they're oxidized. 4G+, And will it give you a boost? 4G+ (frequency aggregation) increases the speed of the Internet by combining several bands, but does not necessarily improve the "permeability" of the signal in the deaf zones. LTE", Your company supports this technology. In the engineering menu, you can try to select LTE CA mode if available. Network reset deletes my photos and contacts? No, network resets (Wi-Fi, mobile networks and Bluetooth reset) only affect network configurations. Your personal files, photos, contacts and applications will remain intact. Only stored Wi-Fi passwords will be removed from other Bluetooth devices. Can the magnetic holder in the car degrade communication? Yes, powerful neodymium magnets in car holders attached directly to the antenna area (usually the upper or lower part of the back cover) can interfere with the radio, if you notice the loss of the radio. 💡The main secret of signal improvement on Xiaomi is a combination of changing the region to the European one, resetting the network settings and, if necessary, manual fixing of the mode. LTE engineer.