Android Phone Updated Last Night -- Cannot Connect To AT&T Cellular Network

Last night a software update was pushed out to my LG Phoenix Plus phone overnight, and upon waking up this morning my phone will no longer connect to the AT&T cellular network. I cannot make phone calls nor send text messages.

Checking my Network status reads the following:

Network - Unknown

Mobile Network Type - Unknown

Service State - Out of Service

Mobile Network State - Disconnected

Steps I have already taken to attempt to address the issue:

Attempted restarting the device, powering off and powering on, cycling through Airplane mode, and booting in Safe Mode -- none of which has fixed the issue.

Performed a factory reset of the device -- did not fix the issue.

Removed, checked and reinserted SIM card -- did not fix the issue.

Checked APN settings to ensure correct information -- settings correct, and did not fix the issue.

Enabled WiFi Calling which DID work briefly and allow me to make and receive calls and texts, then the phone disabled WiFi calling by itself, graying out the option altogether.

Here's my major problem -- the AT&T stores in my city are all shutdown due to government mandate. I can't get tech support on the phone, and at the moment I am the only working individual in my household (wife was laid off due to coronavirus), and I absolutely must have the ability to use this phone in order to keep my job, my family's lifeline right now. I literally cannot replace the device at this time because there is no way to do so, (and may not be able to for months, at least until the restrictions and quarantine on business operations are lifted in my city), and I am certain the AT&T software update is the (Edited per community guidelines) cause of this problem.

Is there any way to roll back a software update? At this point I am willing to try any solution, as my phone is useless to me at the moment.

Many, many thanks in advance for any help or solutions anyone can provide.