Some Galaxy owners are reporting connectivity problems after installing stable One UI 9, including Wi-Fi that keeps disconnecting, mobile data that stops working and, in a few cases, phones that no longer detect a SIM card, Android Authority reports. The complaints come from Reddit and Samsung Community forums, and Samsung hasn’t confirmed a cause or announced a fix. They don’t mean every phone on One UI 9 is affected.
| Problem | Reported on | What users tried |
| Wi-Fi drops with a “connection failed” error, or won’t join 5GHz networks | Galaxy S24 series, Z Fold 7, Z Fold 8 Ultra | Restart or toggle Airplane mode, which only helps for a few hours |
| Wi-Fi calling stopped working (on T-Mobile) | Galaxy Z Fold 7 | Not reported |
| Mobile data stops, apps load only on Wi-Fi | Galaxy S25, S26 Ultra, A16 | Network reset and APN changes, with mixed results |
| SIM not detected, even in Samsung’s diagnostics | Galaxy A56, A36, A52s, S24+ | Restart or toggle Airplane mode, which only helps for a few hours |
A Samsung Community moderator has told affected users to try Safe Mode and contact their carrier, since a major update can require the SIM or eSIM profile to be reactivated. One user says turning off Wi-Fi 7 Mode under Developer Options > Connectivity Labs fixed their Wi-Fi drops, but that option doesn’t appear on every phone and it isn’t a confirmed fix. A factory reset has also been suggested, though at least one user said it didn’t solve their mobile data problem.
If your phone loses its SIM or mobile data, make sure you have another way to make calls available until it’s sorted. Reseating the physical SIM is worth trying, and affected users can send an error report through Samsung Members so Samsung can investigate. If you haven’t updated yet, it may be worth checking feedback for your model first.
This is the latest One UI 9 problem to surface, after Samsung confirmed a Good Lock bug that moves the Galaxy S26 Ultra’s lock screen clock, and the update has already reached models as old as the Galaxy S25.
M Adnan Akram is the founder and lead writer at Phoonomo, covering mobile technology with a primary focus on Samsung and the broader smartphone industry, alongside emerging developments in AI. He follows product launches, spec leaks, and industry trends closely to keep readers informed with timely updates.
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