If you are staying in a DVC villa on points, free internet access is included. The cable is provided. At SSR, ours was in the closet in the master bedroom.
DVC Members get free internet at DVC Resorts, not when staying at non-DVC Disney resorts.
There should be an ethernet cable provided, usually hanging in a bag in one of the closets. If not, call housekeeping/maintenance and one will be provided.