S21 Ultra Mobile Network Issues

[umbnich]

Hi guys,
I've my S21 Ultra having Mobile Network issues since almost two weeks.
I saw it is something that happen to other users. But, how to solve?
I tried changing Sim card, etc.. The issue is clearly the smartphone.

Any idea?

Thank you.

[MW0359944]

How did you send that in? Did you use the Smart Repair service?
My phone is out of warranty (exceeding it 8 months).

[Torashayla]

Mines still under warranty so I sent it to the retailer and they sent it to Samsung 

[Styles]

Hello, I'm also facing this issue right now. Has anyone found a solution?

[Randa N]

Get this repaired yourself if you are out warranty. I had this issue and it was a chip broken and this fixes my issue.  No sim card Change or any software updates fixed this. It is an hardware issue. 

[Styles]

Thank you so much. However, please which exactly chip or board did you change/fix?

[Members_XK4lnVx]

I did the same (in Belgium) and Samsung even warned me that if I send my device again and it turns out that nothing is wrong, they will charge me a fine. So many complaints with the same problem, but they would rather silence you than try to solve the issue.

[Umbs]

Hello Samsung.

Which component we have to replace to fix? Please give us a way to solve or we never trust samsung again.

[Samguy10]

So i have this issue on my s21 ultra and i found out if you go into some special developer network setting section by dialing "*#*#4636#*#*" or using an app called 5g only by vidura prasangana which can be found on the playstore, You can fix it by going into the app, selecting 5g only, go to the smsc section and paste your sim carrier's smsc code and click update then refresh. After that restart your phone then go back to the same area and this time go to the preferred network setting which should be set to "NR/LTE/WCDMA/GSM". Change it to WCDMA only. Now that should make your network fine now. But i wasnt happy with the fact that 5g wasn't working so i decided to keep trying. Now change your preferred network from "WCDMA only" to "WCDMA/GSM preferred". Use that for a few minutes and browse then change it to "LTE/WCDMA/GSM (prl)" and use that for a few minutes then change it back to "NR/LTE/WCDMA/GSM" and you should have it working now. After i did this my network seems to have been fine for the past hour which is longer than it usually is. So im not really sure how well this may work for you but it seems to be working for me. And i can't promise this may work for others aswell but it's worth a try. Let me know if this works for anyone.

[Umbs]

Please explain how

[umbnich · Accepted solution]

Guys, this solved for me (for now):

Open the smartphone from the back, unscrew the sheet which cover the antenna (the "cable" on the right), unplug the antenna, clean the connectors, re-plug the antenna, close carefully everything.

I'm currently posting with 5G of the S21 Ultra.