For such long distances, travelling by bus could not be the best solution. Check out alternatives by plane: with some luck, you will find low-cost tickets from Porto to Lyon and be a lot faster!
When are the buses of the line Porto - Lyon scheduled?
To get to Lyon from Porto by bus, it will take you around 41 hours and 8 minutes, or even 29 hours and 55 minutes if you choose the fastest solutions. The first bus leaves Porto at 13:02, while the last one is at 13:02.
Which bus lines can take you from Porto to Lyon?
There are many companies cooperating with virail, among which also Eurolines with buses to Lyon.