TImezone is ok, I even have it setup so i'm getting NTP from my PDC. Time is dead on.
My unit is
TS-RX6.0TL/R5, the error is
"Failed to Join Active Directory Domain
Please check the Active Directory Domain setting information, Administrator user name and password. Also, make sure that your network settings are correct."
On the DC i'm authenticating to, all logins are done successfully, it looks like it joins OK and then immediately kicks it out.