After gateway replacement, domain shares become offline

A client (An ophthalmologist) suffered a Comcast gateway failure which upon replacement  with a newer gateway stopped the network altogether by disconnecting the firewall, which provided network/DHCP for the doctor's business.

To get the business transacting, I took the firewall out of the loop and established the same network/DHCP scheme as the firewall using the new Gateway. This brought the business back online but  it disconnected all the shares on the client's domain.  They must be manually recreated to be active, and some of the shares lack permissions to do so that were present before the gateway failure/replacement.  I can't figure out why permissions that were present before the gateway change and firewall was taken out.

How to reactivate all the permissions and shares present before the gateway failure and make those many shares active again without recreating them all?

The client is on Windows server 2012 R2 standard.  

The client's (PC's and specialty devices) are all on Windows 10 Pro with the exception of one analysis device that's stuck on 7 Pro.