I gave up on the NFS business and went back to good old buggy but reliable SAMBA (LOL), which is what I was using when I was on Debian 8, and which worked fine. Except for one thing, everything's great.
In /etc/fstab, I have:
//192.168.1.156/BigVol1 /mnt/bigvol1 civs vers=2.0,credentials=/root/smbcreds,ro
That should work, right? Well, it does, but only sometimes. If I boot the system, the remote share isn't there. If I unmount everything with 'umount -a', wait a few seconds, then remount everything with 'mount -a', I sometimes have to do it twice. Sometimes, the first time I get a message from mount about error -95, but if I wait the space of a couple heartbeats and try 'mount -a' again, the share mounts. If I look through /var/kern.log for errors, I don't find anything that stands out as erroneous, but would be glad to supply extracts here that might help me to trace this down and fix it.
TIA