S21 loses 4G connectivity

[Jommy_5]

My Galaxy S21 sometimes loses the internet connection despite showing the 4G icon. Switching airplane mode on and off brings it back for a minute or so, but repeated internet speed tests show progressively lower download speeds,  till it reaches 0. I'm in an area with very strong signal, and even when the connection works it can range from 200 to 20 Mbps in a matter of minutes. I've tried to reset the network settings, and Android is updated. Also changing operator, and hence SIM card, didn't helped.

By Googling the problem there are lots of users that report extremely unstable internet connections. See for example

• 4G Performance on Exynos S21 Ultra is waaayyy slower than an S10+ or S20+ 
• Mobile data not working on s21 ultra 

Are all S21 like mine?

[BandOfBrothers]

One of my work colleague's occasionally experiences mobile data drop outs and call drop outs i.e no service on his Samsung Galaxy s21 Ultra.

However my son who also has the Samsung Galaxy s21 Ultra does not experience these issues with his @Jommy_5 so I'm thinking it's not all Samsung Galaxy s21 are like this or we'd probably see more posts on this forum,  other forums and tech sites etc.

I see you've performed some generic troubleshooting tips.

So I assume this is happening everywhere and not in a particular area ?

If so I can't see this being your local and surrounding masts.

And I see you've tried new sim cards and changed providers so this can't be the sim card or account. 

I also note you've reset the Network Connection which is a good starting point.

The phone has a built-in diagnostic tool via your Samsung Members App under the GetHelp Section and Diagnostic. 

If that comes up as fine then you can send an error report to Samsung via your Samsung Members App. 

And a Samsung Service Centre or Samsung Experience Store can check the phone over to see I this is hardware or software related.

I wish you all the best with this. 

[_Jonno]

I had mobile data issues no signal on 4g and 5g took it to the repairs in Oxford Street they told me to leave the phone there and wait a week or so to get it fixed.

I didn't have a spare phone and declined, I found a spare phone (S20 5g) have zero signal issues and decided to take initiate a repair after three or 4 days in I got told that they couldn't fix it and now waiting 2weeks for a refund how can't they fix they're on devices I don't know...

[Jommy_5]

Hi @BandOfBrothers, thanks a lot for your reply and wishes! Yes, I've seen this behavior in quite a few places. I've tried the Diagnostic tool, and it didn't give any error. I'll try it again next time the connection drops.

On a reddit post, somebody has suggested to change the APN protocol to IPv4/IPv6. I did it, and have not experienced this issue in the last 24 hours. It's a bit early to tell, but maybe the problem is fixed.

Thanks again 🙂

UPDATE a few days later:

No, that did not solved the problem, and the Diagnostic tool does not even start when there is no connection.

UPDATE a week or so later:

I've tried to keep the Diagnostic tool open, and switch to it when Chrome doesn't load pages anymore. I've run the mobile network test, but it claims that it is working properly. I can only conclude that that feature is broken.

[Jommy_5]

Hi @JonJonno, I'm sorry to hear that. Maybe you can try to change the APN protocol to IPv4/IPv6. At least for me it seems to work, so far.

I hope you'll solve this issue soon.

[Hoog]

Yes, my S21 Ultra is the same.
I wished I'd never bought it.
I'm on Three Network in the UK.
I had a Huawei Mate 20 pro for 2 years on Three previous with excellent coverage at all times.
Samsung have been (some) help and Three gave me a new SIM to try, but nothing has worked. Done all the tricks but it keeps going back to poor coverage. Sometimes the phone is totally useless.
Samsung need to admit some of these phones are poor and recall the faulty ones.

[_Jonno]

I got my new phone waiting for the refund now it must've been a hardware issue since they were unable to fix it

[BillJ99x]

I had a similar problem with my S21 Ultra starting right after the August 5th software update. It was resolved with another update later that month. Then two days ago, Oct 5th, I again installed the monthly update and once again I'm having connectivity issues.

Software version is now G998USQS4AUIG

After several hours on the phone with Verizon support I realized that I can access certain sites such as Google.com It turns out that when I'm on mobile data I can only access sites that support IPv6. Sites such as CNN Instagram Netflix etc. I can't reach any sites that are IPv4 only such as verizon.com.

It's a very strange problem and appears to be due to the Samsung monthly software update. All sites work fine on wifi. For mobile data it doesn't matter whether I'm connected to 5G or not, it doesn't work with IPv4. 

Any suggestions? 

[Husn]

I've had the same issue, probably started around the same time as another poster on here, in August. Only thing that works is turning on and off airplane mode!

Did you find a resolution for the issue?

[Jommy_5]

Nope, and differently from what reported above I can't access any site.

I'll have to bring it to a repair center when I can.