I've had my s21ultra since launch with no problems, over the past month though I've differently been getting terrible mobile phone signal. This seems to go from full bars down to 1 to a dreaded 'no service' circle icon with a line through it. Infact, the very act of trying to make a phone call or send a text sometimes kills the signal itself. Or even, it sometime tries to send me a text or can kill my signal. I've tried my sim in other phones, and tried other Sims in my phone, everything points to the phone. Tried network reset, tried loads of mobile network seeing changes, someone's switching airplane mode on and off helps for a while. It can go for a few days being really stable, then have a fit of the network going off, on, off, on, off, on etc. All that also burns down my battery pretty quickly.
If the reset doesn't work then it needs to go for a warranty check. Don't go to a 3rd party as this will void the warranty. Samsung have sophisticated diagnostic tools that may find the issue... could be software or hardware related.
Isn't there a test or diagnostic page on this samsung members app it may have a test option to try on your network drop, also there's a way to get into the samsung test page where you can test most things and it give you answers I can't remember the process to get to this page but I'm sure someone on here or on YouTube would show you and maybe find out if it's a problem..hoe you get it sorted
Yeah I've done the diagnostic thing on the members app, it hit the mobile network bit and sat there spinning for ages while the phone wasn't connected, but as soon as it connected again the diag just moved to the next test and reported no problem. 😕
If its a constant thing then I think it's time to visit a samsung store see what there tech guy says,, hope it's fixed ASAP nothing worse than your phone playing up when your trying to call somebody..keep us posted..