That's not good @StevieDeavs 😐
Does your sim card find connection in another phone ?
Is it possible your phone has failed inside in regards to the part that makes network connection work ,and the recent update has nothing to do with this ?
A Samsung Service Centre will still assess your phone but may levy a fee to repair.
There is also a diagnostic tool in your Samsung Members app you can run.
What troubleshooting / resets have you tried please ?
I appreciate you've tried a Factory Reset.
Have you tried resetting the network connection in General Management ?
Was the security update also connected to a software update ?
If so and your sim card works fine in another phone then and I don't suggest this lightly unless you want to await the next new update to see of that fixes your connection [ send your feedback via your Samsung Members app ] have a look on xdadevelopers.com to find information on how to change software on a phone.
This isn't a process to be taken lightly and needs some homework on the process and importantly there is no guarantee this will resolve the issue.
Using a Custom Rom / trying to use other methods to rollback firmware can bring about an unstable phone or it may not work properly if the process glitches or the wrong Rom is used.
It may stop Samsung Pay from working if the procedure trips your Knox Counter.
A person takes full responsibility if they perform this process and do so at their own informed decision.
Again the process may trip Knox and may affect the Samsung Warranty.
Samsung could levy a charge to put this right or deny support.
It's essential that a person learns on how to do this type of update properly and uses the correct software for their phone and region.
My advice is to wait for the official update via Samsung Smartswitch or via the phone's software update section.
Daily Driver > Samsung Galaxy s²² Ultra 256Gb in Phantom Black.
The advice I offer is my own and does not represent Samsung’s position.
I'm here to help. " This is the way. "