My file/web server is configured and running properly. I have no issues sharing directories via NFS until my firewall becomes part of the equation. But it's not as simple as it sounds...

First off, I'm using ufw and know which ports to open; my ufw config is fine. The /etc/exports file also has the correct configuration for the shared folders. When another computer on the same network is booted up, the NFS shares will not connect as they are configured in /etc/fstab. In order to enable the connection of the shares, the server must have the firewall disabled, then the client can mount the shares (via mount -a). At this point, the firewall on the server can be re-enabled with no ill effects on any of the clients.

That's right: the shares will stay connected after the firewall is re-enabled, but will not connect if the server's firewall is enabled when the client PC boots.

How do I know it's a firewall issue? The other PCs also each have NFS shares that properly connect on boot of any other PC. So the server, the media PC, and the workstation each have NFS shares -- but only the server's firewall causes an issue when either of the other two PCs boot.

Any ideas?