Just got home and tested. Got connect to nfs ok but had permission errors when run the backup. Added no_root_squash and everything worked. Hopefully this will help other users. Thanks
Best posts made by marcusrushy
RE: nfs backup
Think I may have sorted my issue out. I have built 2 VMs are work to test . One with OMV and other with XO. I create an NFS share on OMV and again got permission error. The path I was trying was /sharedfolders/test where your would think it would be but it isn't. It is under /export/test. Changed the path to that and it worked. Will test tonight with a backup to see if I can write to it.