  We review the procedure to construct quasi-free ground states, for real
scalar fields whose dynamics is dictated by the Klein-Gordon equation, on
standard static Lorentzian manifolds with a time-like boundary. We observe
that, depending on the assigned boundary condition of Robin type, this
procedure does not always lead to the existence of a suitable bi-distribution
$w_2\in \mathcal{D}'(M\times M)$ due to the presence of infrared divergences.
As a concrete example we consider a Bertotti-Robinson spacetime in two
different coordinate patches. In one case we show that infrared divergences do
not occur only for Dirichlet boundary conditions as one might expect a priori,
while, in the other case, we prove that they occur only when Neumann boundary
conditions are imposed at the time-like boundary.
