S21 Ultra One UI 4 - Mobile Connection Issue

[djang0U]

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!

If anyone has workable suggestions, I'm all ears.

Thank you.

[sai_virinchi]

Does the new update on Jan 28 2022 solve the issue?

[djang0U]

Go ahead give it a try and experience it for yourself. Feel free to do a factory reset at the same time. 🤣

[Josyn]

Having the same issue after Jan 2022 security patches update on 24 Jan 2022. Very frustrating 🤬

[djang0U]

Welcome to the club! Enjoy your stay.

[Josyn]

I'm using 3G network now, at least I did not encounter any network disconnection issue while still able to surf internet,make call and sms. Most importantly able to scan trace together QR code! Lol!

[sai_virinchi]

Guys any luck?

[ziki77]

No...as Josyn when I am in USB tethering I switch to 3G. The issue is only in 4G mode for me and is not a problem of losing connection but of performance (cannot reach sites).

[djang0U]

One UI 4.1. Go ahead and enjoy. I'll wait for at least 2 months. Enough disappointment from Samsung.

[ziki77]

And....I still have the same issue with USB tethering...

[ziki77]

The issue seems to be resolved after a factory reset.