Owners of the legendary Xiaomi Redmi 4X often face a situation when, after updating the firmware or falling, the device suddenly loses the signal. This is a common problem that can be caused by a software failure in the radio module, and physical damage to the antenna plume. In most cases, you can restore the mobile communication on your own without contacting the service center.
The first thing to do is to eliminate trivial causes, such as malfunctioning itself. SIM-If you have a card or a carrier that doesn't have coverage, if you have a secure network in your neighbouring devices, your Redmi is a good one. 4X It shows "No connection" or "Emergency only" so it's time for a deep diagnostic of the software, and we'll take the algorithm from simple reboots to complex manipulations of the engineering menu.
It should be understood that the hardware of this smartphone, despite its reliability, can degrade over time. Oxidation of the contacts of the sim reader or the de-solding of the antenna is a frequent companion of age devices. However, it is too early to panic: statistics show that more than 80% of network loss cases are solved by competent reconfiguration of program parameters and resetting of network installations.
Basic diagnosis and verification SIM-map
Before you get into the wilds of settings, you need to make sure that the contacts are physically healthy. Turn off your smartphone and remove the SIM card tray. Carefully examine the golden contacts on the map: they should not be scratched, oxides or contaminated. If you use a card that was cut out of the Mini/Micro format with scissors, this may be the main cause of the unstable signal, since the chip may have been damaged.
Try to install yours. SIM-If it works there without any complaints, the problem lies in Xiaomi Redmi. 4X. It's also worth checking if the tray is inserted correctly: it should fit tightly, without gaps. Often users forget that the slot is in the slot. 1 Maybe you're prioritizing it. 4G, And in the second, just 2G/3G.
Clean the contacts with a stripe or soft cloth soaked in alcohol.This is a simple but effective method of removing the oxide film, which prevents normal data exchange between the card and the power controller.
- 🔍 Visually check the integrity of the chip SIM-chip-card.
- 🔄 Try inserting the SIM into the second slot if the first one is not active.
- 📞 Make sure that the map is not installed PIN-Protection that blocks access to the network.
- 📶 Check the card in another device to eliminate operator malfunction.
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Use an adapter to SIM-It is better to replace the card from the operator with a new Nano-SIM format, since older adapters often cause poor contact and loss of network.
Configuring network parameters and modes
Often, the reason lies in the wrong network mode. In today's environment, when operators redistribute frequencies, automatic network type selection can work incorrectly. You need to manually prioritize communication standards. Go to the Settings menu. → SIM-Maps and mobile networks and select the problem card.
Find "Network Type" or "Preferred Network Type." If you have "Preference 4G," try switching to "3G Only" or "2G Only." If you then have "sticks" of the signal, then the 4G module is unstable or overheating. This is a temporary solution, but it will allow you to stay connected.
It's also important to check if the flight mode is on. Sometimes the system freezes in this state, and just switching the tumber doesn't help. Try turning on the flight mode, waiting 10 seconds and turning it off. If that doesn't work, move to reset the network settings, which will return all parameters to factory values without deleting personal files.
☑️ Checking network settings
Resetting to factory settings (Hard Reset)
If software glitches have accumulated in system files, a complete reset will help. It is a radical method that deletes all user data, so backup contacts and photos is mandatory. Reset eliminates driver conflicts that may have arisen after a failed MIUI update.
To perform the reset, go to Settings → About Phone → Reset. Select "Clear Everything." The device will reboot and start the recovery process. In some cases, when the menu is unavailable due to freezing, you have to use a combination of volume and power buttons to enter Recovery mode.
⚠️ Warning: Before performing a full reset, make sure that the battery is at least 50%. Interrupting the firmware or reset process may make it impossible to turn on the device (brick).
Working with APN access points
Incorrect APN settings are a common reason when the phone sees the network but the Internet doesn't work or the "E"/"3G" icon doesn't appear. Operators periodically change the gateway addresses, and the old settings are no longer relevant. You need to create a new access point manually.
Go to Settings. → SIM-maps and mobile networks → Access points (APN). Press the button "New access point" (usually at the bottom or in the menu of three points). Enter the data corresponding to your operator. For most Russian operators, the name of the access point (APN) must match the operator name in the lower case (for example, Internet, mts, beeline).
Once you have entered all the parameters, be sure to click Save and activate the new dot by ticking it. Reboot your smartphone. If you don't know the exact settings for your region, they can be found on the operator's official website or obtained automatically through the operator's website. SMS-request.
| Operator. | Name (Name) | Access Point (APN) | Type |
|---|---|---|---|
| MTS | MTS Internet | internet.mts.ru | default,supl |
| Beeline | Beeline Internet | internet.beeline.ru | default,supl |
| Megafon | Megafon Internet | internet | default,supl |
| Tele2 | Tele2 Internet | internet.tele2.ru | default,supl |
Engineering menu and modem testing
For advanced users, there is a way to check the status of the radio module through the engineering menu, which is a hidden part of the system that allows you to diagnose hardware components. Type in dialer code ##4636#. If the menu opens, select Phone Information.
You can see the connection status here and run the Ping test. If the ping doesn't pass and the signal level is 0 or -110 dBm, the problem may be in the antenna, and you can force the network mode to switch from this menu, for example, to LTE Only, to check if the module holds 4G.
What if the code doesn't work?
Be careful when changing the settings in the engineering menu. Incorrect frequency band configuration can cause the phone to stop seeing base stations at all.
Hardware problems: antenna and plumes
If the software methods didn't work, it's probably the hardware. The Redmi 4X has a design feature: the antenna module connects through contact pads that eventually oxidize or retreat when the case falls. Disassembly requires care, since the back cover is glued.
When disassembling, first of all, look at the antenna connectors on the motherboard. They should be tightly pressed. Also check the integrity of the antenna plume itself, which runs along the body. Often it is rubbed in the places of bends. Replacing the antenna is an inexpensive procedure that often brings the device back to life.
Another possible cause is the failure of the PA (Power Amplifier) or the modem itself, which requires soldering and professional equipment, and if you don't have the skills to work with a soldering iron and a microscope, you better contact the service.
- 🛠 Check the antenna pressing to the body (contact pens).
- 🔌 Examine the antenna plume for tears and scuffs.
- 💧 Look for traces of moisture or oxidation on the board.
- 🔋 Check the voltage on the SIM reader connector with a multimeter.
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If after replacing the antenna and soldering the sim reader network did not appear, there is a high probability of damage to the baseband CPU, which requires complex repairs in the service.