Almost a classic - Netgear should post KB entry on these questions.
Like (almost, with a few exceptions only) all Plus GSxxxxE[n][n] switches, there is no managed core, and no management VLAN, never was. Management access is indeed possible from any VLAN, _and_ on untagged connections only, and in case there is IP access configured only for that specific IP (again on any untagged) connection configured to any VLAN. Tagged connections ie. over a trunk don't allow any management access.
