Train to Porto from Sintra

I would have thought that the train from Sintra goes back to Lisbon and you'd catch
the train to Porto from there. So the question is whether the bus from Sintra is more
scenic than the train from Lisbon.

For me, comfort and ability to move around are as important as scenery. But on the
train you are more likely to be in the countryside, at least some of the time, and the
bus is definitely going to be on the highway.

When we were in Portugal spring of 2023, train workers were striking. We had to take a bus from Porto to Lisbon. It was a comfortable ride, but not scenic.

It is not possible to catch the long distance train from either Cascais or Lisbon. You must go back into the city for the train to Porto. As mentioned, there is a bus you can take that speeds up the process because it leaves from Cascais and Sintra. It’s quite comfortable and actually a bit cheaper than the train. Flixbus is the most common but I’ve also used Gypsy. Both were good.

I took Flixbus from Porto to Sintra. I assume it's the same route, just going in the other direction. It was mostly highway and not what I would call a lovely drive. It was clean and efficient and not expensive though. Still, if it were me, I'd take the train back to Lisbon, then take a train from there to Porto since I find it easier to relax and zone out on a train.

Enjoy your trip!

Thank you everyone for your advise1