Using a relativistic mean-field model calibrated to finite-nucleus observables and bulk properties of dense nuclear matter, we investigate hyperonic neutron-star matter within an SU(3) flavor-symmetry scheme. To retain SU(6)-based couplings within SU(3) flavor symmetry, we add a quartic
ϕ self-interaction and
ϕ-
ρ mixing. We demonstrate the roles of
αv (
F/(F+D) ratio),
θv (mixing angle), and
zv (singlet-to-octet coupling ratio) in SU(3)-invariant vector-meson couplings. It is found that
zv predominantly controls the maximum mass of a neutron star, and
2M⊙ neutron stars can be supported for
zv≤0.15. The
αv also helps sustain large masses, whereas
θv has a smaller effect on neutron-star properties. This SU(3) framework reconciles nuclear and astrophysical constraints, and offers a plausible resolution to the hyperon puzzle.