Found a possible root cause... NetBios (windows ports 137, 138 (UDP) and 139 (TCP) are used to NetBIOS over TCP. TCP445 is used for SMB over TCP.) being disabled and/or blocked on the domain controller. The fix is to disable NetBios and to reset the DC connection on the filer.
The blog post mentions that in some environments NetBios is disabled on Domain Controllers. This would lead to the filer making NetBios requests and not getting a response. Check with your AD team to see if this is the case. I will be checking shortly and will report back if this is the root cause.