Upgrade from 6.5.1 with shares to 6.9.1 doesn't add 6.9.1 features to shares.

Yes.  The 6.5.1 firmware has no support for the NFS root squash function in the gui.  I am guessing because it is Linux that the feature exists for manually configured nfs shares in the OS.

When you use the 6.5.1 gui, Shares, NFS, Advanced, you only see the Async option on / off.

When you use a freshly installed 6.9.1 gui, same place, you also see an option to control the Root Squash as well a the async option.

I have a 6.5.1 system I updated to 6.9.1 in the hope of being able to turn off root squash, and it is still the same as the 6.5.1 gui.

I created a new share, added nfs, and that share on the updated system also has no root squash.

Root squash for those reading (I'm sure you know) allows one to map root accesses from systems writing to the share to a different ID, so you cannot create root owned files on the share.  All such writes by root users are mapped typically to "nobody" on the NAS share.

I'm trying to turn if off to exactly duplicate a volume which has a mess of user id settings on the shares, so that the root owned files and directories on the target are written to the new volume correctly. 

most of the discussions include "why do you need NFS".  I need it.

thanks

Jim