The itinerary lasts 21hrs 15min, and has 2 steps.

Paris - Bayonne
The step from Paris to Bayonne lasts 9hrs 15min. You'll travel in a night train from the company Intercités de nuit.
On board, you'll have access to: Bike, Wi-Fi.

Bayonne - Porto
The step from Bayonne to Porto lasts 12hrs 00min. You'll travel in a night bus from the company Flixbus.
On board, you'll have access to: Wi-Fi.