Hi. If you want to travel by train, you will have to use one of the frequent buses from Dubrovnik in direction of Split. Exit in Ploce and use the train to Sarajevo: https://en.rail.cc/train-connec ... govina/212 I recommend a stop in Mostar. Peter
if you want speed, then use any of the 2-3 direct buses-still not very cheap. As you can go to Dub by bus anyway-check on arrival (the old-age trick that anybody knew before this www came on) its in fact a waste to use an IR for this trip-unless you have spare days left anyway.