Request for mount_nfs assistance

[peter at vfemail.net]

I have two servers funning FreeBSD.  For the past four years, an:

    /sbin/mount_nfs 192.168.0.244:/usr/home1 /home1 

command has successfully allowed one server access to data on the other server's hard drive.  

This morning, following reboots of both servers, the mount_nsf command fails, returns:

    192.168.0.244:/usr/home1: RPCPROG_MNT: RPC: Timed out

error messages.  

Each server can ping the other and connect via ssh; the hardware's working fine; I don't believe anything's changed on either server recently; and the find command doesn't indicate that any system files have been altered in the past week.  

I'm at a complete loss for any explanation of the failure, and I'm uncertain how to diagnose and fix the problem.