Seeing "No Service" or a missing signal icon on your POCO F6 can stop you from making calls, sending texts, or using mobile data. It's a common hiccup that usually has a simple fix, especially on a phone running HyperOS like yours.
The first thing I'd try is a force restart. Just press and hold the power button for about 15 seconds until you feel the phone vibrate and see the POCO logo appear. This clears out any temporary software glitches that might be blocking the cellular radio.
After it boots back up, pull down the notification shade and make sure Airplane Mode isn't accidentally turned on. If it is, tap the icon to turn it off. While you're there, also toggle Mobile Data off and back on.
Check Your SIM Card
Grab the SIM ejector tool that came in the box and pop out the tray. Take out the SIM card and give the gold contacts a quick visual inspection. If you see any dust or debris, gently wipe them with a soft, dry cloth.
Carefully reinsert the SIM card, making sure it's seated correctly in the tray, and push the tray back in until it clicks. A loose or dirty SIM is one of the most frequent causes of signal problems.
Verify Your Network and Roaming Settings
Open the Settings app and go to Connections & Mobile networks. Tap on SIM card & mobile data and select your SIM. Here, you can check a few key things.
First, ensure "Mobile data" is enabled. If you're in an area with spotty coverage from your main carrier, you might need to turn on "Data roaming," but be aware this can sometimes lead to extra charges.
Also in this menu, tap on Preferred network type. For the best balance of speed and coverage, set it to "5G/4G/3G/2G (auto)". If you're having persistent issues, try switching it to "4G/3G/2G (auto)" to see if the more stable 4G network holds better.
Reset Your Network Settings
If the basic checks don't work, the next step is to reset all network-related settings on your phone. This will wipe your saved Wi-Fi passwords, Bluetooth pairings, and cellular configurations, but it won't touch your personal photos or apps.
To do this, go to Settings > Additional settings > Backup & reset. Tap on Reset phone and then select Reset network settings. Confirm the reset and let your phone reboot. Afterward, you'll need to reconnect to Wi-Fi and re-pair Bluetooth devices, but it often clears up stubborn connection bugs.
Update Your APN Configuration
Your Access Point Name (APN) is like the address your phone uses to connect to your carrier's internet. If these settings are wrong or got corrupted, you'll have data issues. Head back to Settings > Connections & Mobile networks > SIM card & mobile data.
Select your SIM and then tap on Access Point Names. If the list is empty or the settings look off, you can usually fix it by tapping the three-dot menu in the top right and selecting "Reset to default." If that doesn't populate the correct info, you'll need to get the exact APN settings from your carrier's website or customer service and enter them manually here.
Use the Phone Information Menu
Android has a hidden diagnostic menu that can be very useful. Open your phone's dialer and type *#*#4636#*#*. This should open the "Testing" menu. Tap on Phone information.
In this menu, you can see the state of your radio. First, check that the "Mobile radio power" is turned on. You can also try toggling it off and then back on. Further down, there's a button to Run Ping Test to check basic connectivity. Near the top, there's a dropdown menu for "Set preferred network type." Make sure it's set to a compatible mode like "NR/LTE/TDSCDMA/GSM/WCDMA."
Check for Software Updates
Xiaomi and POCO regularly release updates for HyperOS that include bug fixes for connectivity and performance. It's worth checking if you're running the latest software, as an update might directly address your signal problem.
Go to Settings > About phone > HyperOS version. Tap the "Check for updates" button. If an update is available, it's a good idea to install it while connected to a stable Wi-Fi network. The Snapdragon 8s Gen 3 chip in the F6 handles updates quickly.
Disable Any Active VPNs
If you use a VPN app for privacy or work, try disabling it temporarily. VPNs route all your traffic through a separate server, which can sometimes interfere with obtaining a local cellular signal or cause conflicts.
You can usually turn off a VPN from its notification or within the app itself. For a more thorough check, go to Settings > Connections & Mobile networks > VPN. If you see any VPN configurations listed here, you can select and remove them.
Manually Select Your Network Operator
Sometimes your phone might be trying to latch onto a weak or incompatible tower. You can force it to search for and connect to your specific carrier. Go to Settings > Connections & Mobile networks > SIM card & mobile data.
Select your SIM and look for an option called Network operators or Choose network. Tap it, and your phone will scan for all available networks in your area. Once the list appears, select your carrier's name explicitly instead of leaving it on "Choose automatically." Wait a minute for it to register.
Test with a Different SIM Card
This step helps you figure out if the problem is with your phone or with your SIM card and carrier account. If you can, borrow a SIM card from a friend or family member who uses a different network.
Pop their SIM into your POCO F6. If you get full signal bars with their SIM, then the issue is likely with your original SIM card or your carrier's service in your location. At that point, contacting your carrier to check for outages or request a new SIM card is the best move.