Cannot join Active Directory with FreeNAS-11.3-U2.1

When trying to join the AD, the error message "NT_STATUS_NO_MEMORY" is shown and the FreeNAS box cannot see any AD users.
I have another FreeNAS box in another Active Directory and there the domain join works. So I don't think that I have any wrong settings.

It MIGHT indeed be the case that the memory is really too low, but that does not seem so to me - at least I didn't see that the memory was exhausted...

Any ideas?

Best regards,
Tom