It was happening with the last release.
I select 5g because I should be able to get 5g. Same sim on my Samsung phone gets me 5g no problem. I keep hoping this phone will be able to do it.
I do have cautiously positive news though: after the update, I turned on location accuracy and it rebooted within 5 minutes, I turned accuracy off and it still rebooted another two times, but since then not once.
Yesterday morning I turned accuracy back on and the total uptime with accuracy both off and on in this way has been 60 hours.
I’m not yet convinced that it’s fixed (that immediate post update behaviour was really weird), but this is definitely a good sign.