I have been using S21 Ultra with Singtel 5G since early this year, and had no issues whatsoever.
After upgrading to One UI 4 on 28 Nov 2021, I have been experiencing severe nonstop mobile network disconnection and mode switching issues on a daily basis.
Below are the details.
1. 5G kept switching to 4G+ and back for no reason.
2. When using YouTube or browser or any app, 5G will suddenly switched to 3G or H+ (which I have never experienced before), and stay at 3G and H+ for more than 10mins.
3. Mobile service completely cut off for no reason. (Happened twice).
Below are what I have tried but still cannot resolve.
1. Reset network settings
2. Switched off VoLTE on SIM 2
3. Reboot into Safe Mode (guided by Samsung Online Chat)
4. Took out Singtel 5G SIM and put into another Android phone to prove nothing wrong with Singtel service.
5. Emailed to Samsung support. But no reply.
My advise to anyone dying to upgrade to One UI 4... Don't!
Hi Faiz, Good day to you. Yes, I have already made an appointment today. Not sure how they can help since it is not a hardware issue.
Interesting, after one day of nonstop trial and error, and rebooting my phone countless times. I discover the issue seems to be with SIM2 after One IU 4 upgrade.
If I disable VoLTE on SIM2 or set network mode for SIM2 to 3G, the issue is resolved. If I reboot my phone, the VoLTE on SIM2 will automatically be started again, which will cause the same problem.
I have been using 2 SIM cards with S21 Ultra with default settings on One UI 3.1 and had no issues.
Kindly escalate this issue to your development team.
The issue is obviously a software problem. So many users experienced the same thing. So going down to service centre is not going to help.
My wife and I bought S21 Ultra, one 256gb one 512gb. Both of us had a terrible time using the phone for the past few months. The network wld drop and a "no network" symbol wld pop out multiple times a day. It has nothing to do with telcos or 5G SIM card too. I'm using 5G sim card from Starhub and a 4G card from TPG. Both networks wld drop.
It is very frustrating coz we paid top dollars for supposedly the best phone yet the experience is the worst so far. I have used S6, S8+, S9+ and S10+. All of them were cheaper but none gave me such problem. Until the bug is solved, pls avoid this phone at all cost.
I have network issues after update to one ui 4.0 with mobile network too! Mobile Hotspot and usb tethering performance are very poor after the update. Slow speeds, high ping, network disconnections. EUR firmware Greece.
