Dell VRTX and active directory authentication

I have an issue on a Dell VRTX 2.01.

I have 2 VRTXs and one of them i have managed to add Active Directory authentication. However on the other i cannot get it to work. Settings on both seem to be the same however i never get the option to login to the domain.

I am using standard AD (not extended) - i have added the IP addresses of GC/AD DCs on both VRTX and also the group from the relevant domain. However as stated above on 1 of the VRTX this works and i can login. On the other i dont get the option to login.

Anyone seen this behaviour?

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