  In the context of the $\mathrm{SU(3)_c \otimes SU(3)_L \otimes U(1)_X \otimes
U(1)_{N}}$ (3-3-1-1) extension of the standard model, we show how the
spontaneous breaking of the gauge symmetry gives rise to a residual symmetry
which accounts for dark matter stability and small neutrino masses in a
scotogenic fashion. As a special feature, the gauge structure implies that one
of the light neutrinos is massless and, as a result, there is a lower bound for
the $0\nu\beta\beta$ decay rate.
