Just an FYI for those of you who might be traveling from the Lisbon area to Porto in the future.
Scotturb - the local bus company for Cascais and Sintra - has announced a new express service from Cascais and Sintra to Porto for € 5,90. They are advertising the buses as having WiFi and bathrooms. The total time from Cascais is under four hours.
For anyone wanting to go from either Cascais or Sintra to Porto , this would be cheaper and much easier than going back into Lisbon to catch the train. The service starts 27 September, and there are four departures per day.