Galaxy S23 Ultra - Issue using 4g and 5g network after ONE UI update 6.1

[Ritz2425]

I am having the problem using 4g and 5g network on my recently purchased S23 ultra. I updated my device to the latest One UI (version 6.1) yesterday (8th September 2024) and post that I am not able to connect to 4g or 5g network. I am unable to do any transaction when I go outside. The place I use the device is the same place I have been staying for 10 long years. It bought it recently (August 1st week 2024). Issue started yesterday when I went outside and tried to do a UPI payment in Bangalore India. The network provider is the same and I have enough data left on my number. Please resolve this ASAP since its very difficult to use for anything outside my house. 
Device details: Galaxy S23 Ultra.

[AndrewL]

@simonhardcastle: This indicates that you are outside the region where you registered with your mobile network. Alternatively, please head to Settings > Connections > Mobile networks > Data roaming, and toggle this option off. 

[Jordans23ultra]

Hey there andrew I don't know if you'll reply, but like I'm having trouble with my s23 ultra network i tried to rest network settings etc & I have putted my simcard in another of my older samung devices and it works completely fine especially 1 or 2 bars out of 4 but when my s23 ultra goes 3 bars its really good n fast with that but when it goes to 1 or 2 doesnt work and aswell my 5g doesn't even work way too slow my 3g network is faster than my 5g. I've tried everything expect prem restarting s23 ultra device do you have any recommendations to fix this issue cheers mate, Jordan