In a large saucepan over medium-high heat, combine wine, port, sugar, cinnamon stick, vanilla seeds and pod, and salt. Bring to a boil, stirring until sugar dissolves. Reduce heat to medium-low and add dried plums. Keep mixture at a gentle boil until liquid is syrupy, about 45 minutes. Let cool at least 15 minutes. Discard cinnamon stick and vanilla pod. Roughly chop or slice 18 plums.