As Microsoft Server needs to be the DHCP/DNS server this can be an issue for remote offices/workers.
Windows domain controllers normally get set up with a .local or such name which is not resolveable in the real world.
Open Advanced => DHCP / DNS Server (LAN)
in the Custom configuration box add the following lines.
This way real DNS queries head off to the local internet & local DNS queries are sent to your DC for correct resolution.
Solved a lot of issues for me, hope this helps someone else.