Key Takeaways
- Check Your Connections: After One UI 9, your Galaxy may drop Wi-Fi, load apps only on Wi-Fi, or show “No SIM.” Samsung hadn’t confirmed the cause or a patch as of November 10, 2026, so check your carrier, router, Mobile data toggle, and SIM manager first.
- Try Targeted Fixes: On One UI 9, restart, toggle Airplane mode, and rejoin Wi-Fi if you see “Connection failed.” Disable Intelligent Wi-Fi switching, reset Wi-Fi and Bluetooth or mobile networks, and check Network mode and APN before testing the owner-reported Wi-Fi 7 Mode, VoLTE, or 5G Standalone workarounds.
- Report Recurring Drops: If One UI 9 keeps dropping connections, reseat your SIM, test in Safe Mode, and report it through Samsung Members with Send system log data selected. A factory reset can erase your data and leave the drops unresolved, so use whichever connection works and check for updates.
One UI 9 mobile data not working after your Galaxy updated? If your Wi-Fi also keeps dropping or your phone suddenly says “No SIM,” you may be running into a widely reported One UI 9 connectivity bug. As of November 10, 2026, Samsung hasn’t publicly acknowledged the bug or confirmed a patch for it.
Start by checking your carrier, router, and SIM, then try the network resets that match your symptoms. If the drops continue, you can try owner-reported workarounds such as turning off Wi-Fi 7 Mode or briefly testing with VoLTE off. If the problem returns, send an error report through Samsung Members. Some owners still had connection problems after a factory reset.
What’s Going Wrong With One UI 9 Connectivity
With One UI 9 mobile data not working, you might find that an app loads the moment you reconnect to Wi-Fi. For some Galaxy owners, it’s the other way around. Their phone can use mobile data, but home Wi-Fi drops after an hour or two and shows “Connection failed.” Match what you’re seeing to a first check below.
| Symptom | What you see | Fix to try first |
|---|---|---|
| Wi-Fi keeps dropping | Your phone loses its connection after an hour or two or shows “Connection failed” | Forget and rejoin the Wi-Fi network |
| 5 GHz Wi-Fi fails | Your Galaxy connects on 2.4 GHz but struggles on 5 GHz | Test both bands on another device connected to the same router |
| Mobile data or 5G stops working | Apps load on Wi-Fi but stall when you switch to mobile data | Check that Mobile data is on and that SIM manager has the right SIM selected |
| Your phone says “No SIM” | Your Galaxy stops recognizing the physical SIM | Check SIM card status and run the SIM test in Samsung Members |
| Wi-Fi calling stops | Your Galaxy stays connected to Wi-Fi, but Wi-Fi calling fails | Check with your carrier about Wi-Fi calling on your line |
Which Galaxy Phones Are Affected
Owners have reported connection trouble on the Galaxy S24, S24+, S24 Ultra, S25, and S26 Ultra, as well as the Galaxy Z Fold 7 and Z Flip 7. Reports also cover the Galaxy A56, A55, A36, and A52s. The problems have appeared on both Exynos and Snapdragon phones.
Wi-Fi trouble comes up more often than mobile data failures, and “No SIM” reports are rarer still. Some owners have reported trouble with T-Mobile 5G or Wi-Fi calling, while an Xfinity Mobile customer reported a data failure during the One UI 9 beta.
Has Samsung Fixed It Yet
Samsung’s November 2026 security update started rolling out in early November and included Exynos modem security fixes. As of November 10, Samsung still hadn’t confirmed a fix for the Wi-Fi, mobile data, or SIM drops. Not sure your model has the update yet? Check which Galaxy phones have One UI 9.
Open Settings > Software update > Download and install to check for a pending update. Read the changelog, install any available update, and test the connection that was giving you trouble.
Quick Checks Before You Reset Anything
Did your Galaxy start dropping connections right after One UI 9 installed? The timing makes the update worth investigating, and a few checks can help you tell whether your router, carrier, or SIM is involved. Start with the connection that keeps failing.
Rule Out Your Carrier and Router
If mobile data or Wi-Fi calling fails, ask your carrier whether there’s a service problem or whether your line needs attention. If you recently switched carriers, your new carrier might have to refresh your phone on its end. For a SIM that stopped working after a move to another phone, ask whether SIM protection is active.
If Wi-Fi is the problem, try the same network on another device and see whether your Galaxy can connect to a different saved network. Unplug your router and modem, plug them back in, and test again. If your router shows separate 2.4 GHz and 5 GHz networks, try both on your Galaxy.
Check SIM Manager and Mobile Data
Open the Quick panel, also called Quick settings, and check that Mobile data is on. Then go to Settings > Connections > SIM manager. If you use two lines, check that the SIM you want is selected for mobile data.
If your Galaxy says “No SIM,” go to Settings > About phone > Status information > SIM card status. Check whether your carrier appears under Network. You can also open Samsung Members > Support > Get Started > SIM and follow the prompts to see whether the phone detects the card. Samsung’s own steps for a No SIM card error cover the basics, and our guide to a SIM card not detected on Android covers the hardware side.
10 Fixes for One UI 9 Mobile Data, Wi-Fi and SIM Problems
Start with a restart, then work through the steps that match the connection you’re losing. Try one change at a time and retest the same network or app after each one. Begin with a fresh connection before clearing any saved network information.
1. Restart and Toggle Airplane Mode
Open the Quick panel and tap the Power icon, then tap Restart. If the screen is unresponsive, hold the Side key and Volume down together for more than seven seconds to restart your Galaxy.
Once the phone is back on, open the Quick panel, turn Airplane mode on, then turn it off again. Give your Galaxy time to reconnect and open an app that was failing on mobile data. Some owners got their connection back briefly with a restart or an Airplane mode toggle, so check again if the same symptom returns.
2. Forget and Rejoin Your Wi-Fi Network
Go to Settings > Connections > Wi-Fi and tap the gear next to the network that keeps dropping. Tap Forget to remove the saved connection. Have the Wi-Fi password handy before you do this.
Select the network again from the Wi-Fi screen and enter its password. Wi-Fi passwords are case-sensitive, so check the capitalization if your Galaxy won’t join. If the connection usually drops after an hour or two, keep using it long enough to see whether the problem returns.
3. Turn Off Intelligent Wi-Fi Switching
Go to Settings > Connections > Wi-Fi, tap the three-dot menu, and open Intelligent Wi-Fi. Try turning off Switch to mobile data, Switch to better Wi-Fi networks, and Turn Wi-Fi on/off automatically.
If your Galaxy tends to drop off your home network while another saved network is nearby, start with Switch to better Wi-Fi networks and test the connection again. Treat these switches as a workaround to test. You can restore each one if changing it makes no difference.
4. Reset Wi-Fi and Bluetooth Settings
Open Settings > General management > Reset and look for Reset Wi-Fi and Bluetooth settings. Tap it, then tap Reset settings. Depending on your Galaxy model and region, you may see a single Reset network settings option that clears Wi-Fi and Bluetooth information as part of a combined reset.
The reset clears saved Wi-Fi passwords and Bluetooth pairings. If Bluetooth or keyboard bugs also showed up after the update, our One UI 9 problems guide covers those. Rejoin the Wi-Fi network that was dropping and test it before setting up your other connections again. Some owners regained connectivity after a network reset, while others saw the same drops afterward.
5. Reset Mobile Network Settings
Go to Settings > General management > Reset > Reset mobile network settings, then tap Reset settings and Reset. If your model and region use the combined Reset network settings option, choose that label and follow the same confirmation steps. If you already ran the combined reset in the previous step, move on to the network mode and APN checks.
Your Galaxy reconnects using its default mobile network configuration, and your apps and personal data stay on the phone. Try opening the affected app over mobile data again. If your phone still can’t get online, your carrier may need to send its network configuration to your Galaxy again.
6. Check Your Network Mode and APN
Open Settings > Connections > Mobile networks > Network mode. If 5G keeps dropping, try the 4G/3G/2G option in place of 5G/4G/3G/2G, then restart and test mobile data. Your phone may say LTE instead of 4G, and your carrier or software version may hide some modes.
If apps still load only on Wi-Fi, return to Mobile networks and open Access Point Names. Tap the three-dot menu, then choose Reset to default if that option appears. Test mobile data again with Wi-Fi turned off.
7. Turn Off Wi-Fi 7 Mode
Some Galaxy owners reported fewer Wi-Fi drops after turning off Wi-Fi 7 Mode. This is an owner-reported workaround, and the toggle is missing on some older and midrange models. If your Galaxy shows Wi-Fi 7 Mode, turn it off and test the network that usually drops.
On some phones, owners found the switch under Developer options > Connectivity Labs. To enable Developer options, go to Settings > About phone > Software information and tap Build number seven times. If you don’t see Connectivity Labs there, open Settings > Connections > Wi-Fi, tap the three-dot menu, and open Intelligent Wi-Fi. Tap Intelligent Wi-Fi at the bottom seven times to reveal Connectivity Labs, then check whether Wi-Fi 7 Mode appears.
8. Test With VoLTE or 5G Standalone Turned Off
Open Settings > Connections > Mobile networks and look for the VoLTE switch. Its wording can vary by carrier and region. One Galaxy S25 owner reported that turning VoLTE off helped, but keep the test brief. Turning off VoLTE can break voice calls where 3G has been shut down, so turn it back on after testing.
If you see 5G Standalone in Mobile networks, you can test that switch separately. An Xfinity Mobile customer with an unlocked Galaxy S26 Ultra reported that turning it off restored data during the One UI 9 beta. Both tests come from owner reports, so check whether either one makes a difference on your line.
9. Reseat Your SIM or Reinstall Your eSIM
If your Galaxy says “No SIM,” use the eject pin to open the tray and remove the Nano-SIM. If the card needs cleaning, wipe it with a soft, dry cloth and avoid touching the gold contacts with your fingers. Dry the tray if it’s wet, then reseat the card with the gold contacts facing up and check whether your carrier appears under SIM card status.
If you already use an eSIM, check with your carrier about reactivating it before you reinstall the profile. Go to Settings > Connections > SIM manager > Add eSIM and use Scan QR code or Enter activation code, depending on what your carrier provides. If your physical SIM still goes undetected, some owners reported getting service back by switching to an eSIM. Check whether your carrier supports Convert to eSIM or can provide an activation code.
10. Test Your Phone in Safe Mode
Open the Quick panel and tap the Power icon. Touch and hold Power off until the Safe mode icon appears, then tap Safe mode. Look for “Safe mode” at the bottom of the screen after your Galaxy restarts.
Reconnect to the Wi-Fi network that keeps dropping and see whether it stays connected. If Wi-Fi works in Safe Mode, a downloaded app may be involved. If the connection drops there too, note what failed so you can include it in a Samsung Members error report.
If Your Connection Still Keeps Dropping
Did your Galaxy reconnect after a restart or network reset, only to drop again an hour later? If you’ve tried the steps for the connection that keeps failing, the next drop gives you a chance to capture what happened. Start by sending an error report with system logs through Samsung Members.
Send an Error Report Through Samsung Members
As soon as the connection drops, press and hold the Samsung Members app icon and select Error reports. Choose the category that best fits the problem and describe what you were doing when the connection failed. Include your Galaxy model, carrier, and any message you saw, such as “Connection failed” or “No SIM.” If you caught the error in a screenshot, use the paper clip to attach it.
Select Send system log data and tap the send arrow. Aim to submit the report within three minutes of the drop if you can. Leave Samsung Members open until the upload finishes, which can take about five minutes.
Why a Factory Reset or Rollback Isn’t the Answer
A factory reset wipes your Galaxy’s personal data, and some owners still needed Wi-Fi to load apps after resetting their phones. If you’ve already tried the network resets and tested in Safe Mode, send a Samsung Members error report before you consider erasing your phone.
As of November 10, 2026, Samsung hasn’t confirmed a way to roll back to One UI 8.5 for this connection bug. If your Galaxy is already on One UI 9, go to Settings > Software update > Download and install to check for a newer build. Read the changelog for any mention of the connection that keeps failing.
What to Do Next
It’s frustrating when an app works at home and stalls as soon as you step outside. If your battery is also draining faster since the update, try our One UI 9 battery drain fixes. If Wi-Fi or mobile data is still reliable, use that connection for now. When the other one drops again, note what happened so you can capture it in a Samsung Members report.
If a restart, reset, or switch got you back online, give the connection some time under the same conditions that used to cause trouble. When a new update arrives, retest the same app or network. You’ll have a clear sense of whether your Galaxy can stay connected again.
FAQs
Your Samsung Galaxy may only load apps on Wi-Fi because its mobile data connection is failing after the One UI 9 update. Samsung hasn’t confirmed what causes the failure. Check that Mobile data is on in the Quick panel, then open Settings > Connections > SIM manager to check which SIM handles mobile data.
A factory reset has failed to restore mobile data for some Galaxy owners on One UI 9. Since a factory reset erases your personal data, try Reset Wi-Fi and Bluetooth settings or Reset mobile network settings first, depending on which connection fails. On some models and in some regions, the combined option is called Reset network settings.
Samsung hasn’t confirmed a rollback to One UI 8.5 for the One UI 9 connection bug. If your Galaxy keeps dropping Wi-Fi or mobile data, check Settings > Software update > Download and install for a newer build and report the drop through Samsung Members.
Your Galaxy can show “No SIM” after One UI 9 even when the card works in another phone because the Galaxy may be failing to detect it. Open Settings > About phone > Status information > SIM card status and see whether your carrier appears under Network. You can also run the SIM test in Samsung Members or ask your carrier whether SIM protection is active if you recently moved the card.
As of November 10, 2026, Samsung hasn’t confirmed a fix for the One UI 9 Wi-Fi, mobile data, or SIM problems. The November security update included Exynos modem security fixes. Check the changelog under Settings > Software update > Download and install for any mention of a connectivity fix.
Wi-Fi calling can stop working after One UI 9 even while your Galaxy stays connected to Wi-Fi, and Samsung hasn’t confirmed why. A T-Mobile customer reported this on a Galaxy Z Fold 7. If your other apps work on Wi-Fi, ask your carrier to check Wi-Fi calling on your line and include that detail in your Samsung Members report.
