I installed omv 4 on vbox and hardware with 3ware controller. After installing 3dm2 and tw_cli, the 3dm2 service is started but didn`t listen on port 888.
3dm2.conf: Remote enabled, port 888, service restarted.
On omv 3 no problems.
On debian 9 (nativ on VBOX) it worked, so my guess, it is omv4 related.