Hey,

you can add it manually. Check the times on the website of vy and add it.
You’ll need a reservation for this train AFAIK, either by calling Entur via phone or making it at a station in Norway.

Thank you, Martin M! This helps!

I think its not VY but maybe Go-Ahead that now runs the contract on this NO-southern line?

Again: use bahn.com-much batter and wider coverage-will also show if RES is mandatory/optional or not poss.

Except that in this case, bahn.com didn't know these timetables either. Which you would have know if you'd have checked.