We are taking the train from Lisbon to Sintra for several days. Will we then be able to take a train directly from Sintra to Porto and if so how long is that trip? Jay
You will normally connect trains both at Lisboa Oriente and at Porto Campanha station to get to the more central Porto Sao Bento station, or you can take metro or taxi from Campanha to your hotel neighborhood. A few departures connect at Entrecampos instead of Lisbon.
Looking Up Train Schedules and Routes Online gives you the Deutsche Bahn train schedule link and tips for using it. Or the Portuguese railway site is www.cp.pt.