I have a WS2K12 R2 server that is serving a NFS accessed by CentOS 7 / RHEL 7 if I turn my Firewall off it works with it on it doesn't.
Question Is: What are the ports required for the NFS Share (TCP / UDP) (In / Out).
These services are defined within the /etc/services file. I believe the port you're looking for is 2049 tcp and udp. Good luck.