  In this paper, we study massless/massive vector and $p$-form field
perturbations in AdS spacetime with an end-of-the-world brane. By imposing
$U(1)$ preserving Neumann boundary condition on the end-of-the-world brane, we
study their spectrum and discuss their implications for dual BCFT operators.
When the perturbation is massless, the dual BCFT operator is a conserved
current and we show that such an operator indeed satisfies the $U(1)$
preserving conformal boundary condition. On the other hand, when the
perturbation is massive, in general there exists non-vanishing perpendicular
components of the dual BCFT operator, even in the massless limit. We explain
this difference between massless and massive perturbations from the point of
view of the bulk gauge symmetry, or equivalently from different structure of
equations of motion. We also find several brane-tension-independent modes in
massless perturbations, and these are understood as
boundary-condition-independent modes from the dual BCFT point of view.
