Went by bus from Bahir Dar to Addis Abeba and by plane to Khartum.
And with the weekly train to Wadi Halfa and the boat to Assuan. This train did have a unclear departure time. Fortunately i had a 1. class ticket, the compartment i was in had holes in the floor and some other problems, but in the 2. class fish was transported, quite smelly in about 40° Celsius. After a very slow journey the train arrived finaly in Wadi Halfa the next day, from there by boat to Assuan.