The situation when a smartphone suddenly stops detecting wireless networks or loses connection at the most inopportune moment is familiar to many owners of budget and mid-range devices. Model Samsung Galaxy A21sDespite its popularity, it's not without software quirks that can cause conflicts with the communications module. Most often, the problem stems not from a physical antenna failure, but from a software glitch in the accumulated cache or incorrect DHCP settings.
Users often encounter problems with their phones either not detecting the router at all or endlessly attempting to obtain an IP address. This can occur after an operating system update. One UI or changing providers. It's important to understand that restoring functionality requires a consistent approach, from simple reboots to a complete reset of network settings.
In this guide, we'll examine all possible causes of the problem and offer specific troubleshooting steps. You'll learn how to diagnose software conflicts, properly configure a static IP address, and when it's time to consider flashing your device. Service center statistics show that 85% of such problems are resolved by a software reset of the network without resorting to repair.
Diagnosing software failures and flight mode
The first step in troubleshooting any network issue is to check the system's basic functions. Sometimes the Wi-Fi module simply freezes in the background and stops responding. To do this, simply enable airplane mode. Go to the notification shade and tap the airplane icon. Wait 10-15 seconds, then disable it. This will force a restart of all radios, including Bluetooth and cellular.
If a simple module reboot doesn't help, you'll need to perform a full operating system reboot. On smartphones Samsung This often resolves issues with frozen system processes blocking drivers. Hold down the side button and select "Restart" from the menu that appears. Don't skip this step, as it clears temporary errors from your RAM.
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⚠️ Caution: If the phone heats up near the camera after rebooting, this may indicate a short circuit in the Wi-Fi module's power supply. In this case, further software interventions may be futile.
Check if the internet is working on other devices connected to the same access point. This will help rule out issues with your ISP or the router itself. If the network is stable on your laptop or tablet, then the problem is localized to your device. Samsung A21s.
Reset network settings and clear cache
The most effective software solution is to reset your network settings to factory defaults. This doesn't delete your personal files, photos, or contacts, but it does erase saved Wi-Fi passwords, Bluetooth settings, and mobile network settings. To perform a reset, go to the menu Settings → General settings → Reset.
In the list that opens, select "Reset network settings." The system will warn you that your Bluetooth and Wi-Fi data will be deleted. Confirm the action by entering your PIN or unlock pattern. Once complete, the phone will reboot, and you will be required to re-enter your wireless network password.
☑️ Checklist before resetting the network
Another important step is clearing the system cache, which may have become corrupted. Go to Settings → ApplicationsIn the menu (three dots in the corner), select "Show system apps." Find "Wi-Fi" or related services in the list (for example, WlanService). Go to the "Memory" section and click "Clear cache".
- 📱 Clearing the cache frees up space for communication drivers to function correctly.
- 🔒 Resetting settings removes conflicting static IP configurations.
- ⚙️ Restarting Google Play services often resolves network certification issues.
Problems obtaining an IP address and DNS
A common mistake owners face Samsung A21s — the "Obtaining IP address..." message that continues forever. This means the router sees the phone but can't assign it a digital address on its local network. This is often caused by an overflowing DHCP client table on the router or an address conflict.
To resolve this issue, you can try manually assigning a static IP address. In the list of available networks, click on your Wi-Fi network and select "Forget" or "Delete." Then click on it again to connect. In the settings window that appears, find "Advanced" or "IP Settings." Switch the mode from DHCP to "Static."
You will need to enter the following data (approximate, depends on the address of your router):
IP address: 192.168.1.128Gateway: 192.168.1.1
Network prefix length: 24
DNS 1: 8.8.8.8
DNS 2: 8.8.4.4
Using Google's public DNS servers (8.8.8.8) often helps if the problem is caused by blockages or errors on your ISP's DNS server.
Why does IP conflict occur?
A conflict occurs when two devices on the same network attempt to use the same digital address. The router becomes confused about which device to send data to and blocks the connection for both devices. A static IP address solves this problem by assigning a unique number to each phone.
Impact of One UI and Android version updates
Smartphone software is constantly updated, and sometimes new versions One UI contain errors that affect the stability of the Wi-Fi module. If the problem appears immediately after a system update, there's a high probability that the current firmware is incompatible with the wireless drivers.
Check for new updates in the section Settings → Software Update → Download and Install. Company Samsung regularly releases security patches and bug fixes. If the update has already been installed and the problem persists, you can try resetting the settings to factory defaults via Recovery Mode, but this is a last resort.
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⚠️ Note: The menu interface and item names may vary slightly depending on the Android version (10, 11, 12) and regional firmware version. Always consult the latest user manual for your software version.
Sometimes disabling the Wi-Fi Power Saving feature can help. It's designed to save battery life, but on some models, including A21s, may prematurely disable the communication module. You can find this option in the advanced Wi-Fi settings or in the "Battery" section.
Diagnostics of the 2.4 GHz and 5 GHz frequency ranges
Modern routers often operate in two bands: 2.4 GHz and 5 GHz. Smartphone Samsung Galaxy A21s supports both standards, but situations may arise when it “prefers” the overloaded 2.4 GHz range, ignoring the faster 5 GHz, or, conversely, does not see the network due to channel incompatibility.
In your router settings, you can try separating the network names (SSIDs) for different frequencies by adding the suffix "_5G." Then, connect to the desired network on your phone. You should also try changing the broadcast channel in your router settings to a less congested one (for example, 1, 6, or 11 for 2.4 GHz).
Comparison of range characteristics to understand the problem:
| Parameter | 2.4 GHz band | 5 GHz band |
|---|---|---|
| Range | Tall, breaks through walls | Low, poorer penetration through obstacles |
| Speed | Below, often overloaded | High, stable |
| Compatibility | Works with all devices | Requires module support |
| Interference | Many (microwaves, Bluetooth) | Minimum interference |
Hardware faults and module soldering
If software methods, including a hard reset, do not produce results, there is a high probability of hardware failure. In the model Samsung A21s The Wi-Fi module is often integrated into the main board or is a separate chip soldered to the motherboard. Drops or impacts can cause the module to lose contact.
Another possible cause could be a faulty antenna module or the cable connecting the antenna to the board. The antenna output on this model is located at the top of the case. If the phone was dropped at this angle, the risk of antenna damage increases.
- 🔨 Mechanical damage to the board after falling or being crushed.
- 💧 Moisture getting inside the case, causing oxidation of the contacts.
- 🔥 Processor overheating, leading to solder delamination under the Wi-Fi chip.
Frequently Asked Questions (FAQ)
Why does Samsung A21s see Wi-Fi but not connect?
Most often, this is caused by an incorrect password stored on your phone or an IP address conflict. Try "Forgetting" the network and re-entering the password. Also, check if your router is set to MAC address filtering.
How to reset network settings without losing photos?
The "Reset Network Settings" feature in the Samsung menu only deletes connection settings (Wi-Fi, Bluetooth, and Mobile Network). Your personal data, photos, contacts, and apps will remain intact. However, you'll have to re-enter your Wi-Fi passwords.
Can a virus block Wi-Fi on a Samsung?
Theoretically, yes, malware can change network settings or block the communication module. It is recommended to scan the phone using Google Play Protect or install a reliable antivirus scanner.
What should I do if Wi-Fi is slow only on my phone?
Check if power saving mode, which limits background activity, is enabled. Also, try changing the DNS servers in your Wi-Fi settings to 8.8.8.8. Your phone's antenna may be damaged or being shielded by a case.