My s10 was having the same problem, after I did that, works great.
If you have a stock Samsung S10 (meaning not a branded carrier model), the keypad code to enter Data Programming Mode is
Hope that helps someone! Wish Samsung would fix this stupid problem.
Regardless of your carrier, if your S10 is still experiencing sudden (and persistent) connectivity drop-outs in seemingly strong signal reception areas, contact your carrier or visit one of their repair centers to have your device tested (Sprint, for example, can test for mobile data connectivity hardware failure at their repair centers) to find out if you're dealing with a faulty/defective device. UBreakiFix is authorized to repair/diagnose Samsung products, so if you have one in your area that is an option as well.
In many (if not most) cases, software will be the culprit. Always test the device in Safe Mode (press power button then hold down power-off icon to bring up Safe Mode) to rule out 3rd-party apps as the problem. Wiping the cache partition (go into Recovery mode - power off S10, power on pressing the volume up + Bixby button + power button until Recovery loads) will also help resolve various issues that can affect the stability of the firmware. When all else fails, a factory data reset will wipe the slate clean and help narrow down hardware vs software problems. If you back up to Samsung Cloud or use Smart Switch to back up data to a PC/Mac, running a restore after factory resetting is fairly simple (and relatively fast) and will bring your S10 back to the state it was in when it was backed up.
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Just FYI, a Sprint repair facility diagnosed a hardware failure in my S10+, but Samsung insisted that I bring it to Ubreakifix, who insisted that the phone just needed to be reflashed. It was a hardware failure that required a board replacement. Ubreakifix was useless in my case and caused me to waste more time.
This issue is marked as 'Solved' but it isn't. At least be honest enough to avoid pretending this issue is resolved. I have an unlocked s10e on Verizon that intermittenly loses internet over both wifi and 4G across all apps. It happens randomly (twice in the last 12 hours) and reboots/shutdown restarts do not fix the issue. I was driving to a doctors appointment and had to call my girlfriend for directions because my $750 phone decided to turn into a brick on the highway.
The problem is not my wifi. The problem is not my cell signal. The problem has not been fixed with software updates. I've had half a dozen devices (pixel, iphone x, etc.) over the last 3 years (work and personal phones) and have never had an issue even close to resembling this. I will try to go into Verizon to see if they can diagnose and update.
Also, the name 'UBreakIFix' is annoying in this context. How about 'SamsungBreakSamsungMaybeFix.'
Just picked up the note 10+ today and I'm having similar issues with wifi and mobile, never once had an issue on my s8+
Edit: I did what user userDtcCY6S4Ny suggested a few messages up and it works for the note10+
This has NOT been resolved. I've tried all the settings and check to verify I have the latest updates. I have to disable WIFI in order to get connection to the internet. WHERE'S THE FIX.....
I will tell you this is not a Samsung issue. I have Verizon and even with my old Motorola phone I could not force WiFi calling, it's the carrier. Where I live I might get one bar of 3G with Verizon depending on which way the wind blows, or maybe 1x data, but it jumps around so much it basically disables the ability to use WiFi calling since you cannot force it due to carrier restrictions. It is preferred only, but the network will ALWAYS prefer a cellular signal over WiFi for whatever reason. It is ridiculous yes, but not a Samsung or phone maker issue. I ended up getting an extender through Verizon for free because of it.
I should also probably point out that Verizon is retiring their CDMA service as of January 1st. It will continue to work only for existing customers until they replace their phones. That leaves Sprint as the only CDMA carrier left because the technology is inferior and has already been abandoned by everyone else who previously used it.