hfss subwavelength

I want to simulate the paper "Influence of hole size on the extraordinary transmission through subwavelength hole arrays", but there is always an error:[error] Port 'FloquetPort1': The exterior boundary of the faces for a Floquet Port must consist of pairs of parallel and equal length segments, displaced from each other by an integer linear combination of the lattice vectors. May I ask how to solve this problem? Who can help me with a project? Thanks a lot.