I update the software and network mode doesn't work. I changed the Sim and did a factory setting, but it still doesn't work.
You're trying to change the network mode (i.e., 4G, 5G, etc.) and there is no option to do so? Have you reached out to your carrier about this yet?
Ah, I see that. How strange. Your carrier controls this functionality, so they should be able to shed some light on the problem. It might not be possible to switch network modes through your mobile provider.
It's only a Verizon issue. Don't let them pawn this off on Samsung. Only they control the ability to select network modes. It's specific for each carrier.