Hello Dan,   It's difficult to triage such issues w/o the logs.  I would suggest opening a support case with Dell for this issue.   Regards,   Don 
FS 7x series trying to join a nas cluster  to the domain and im getting "cluster already exist in the domain , leave the domain and join again" i see no traces for it in AD , and in group manager it doesnt say leave domain it only says configure AD 
FS NAS CLUSTER cannot join domain