I think i may have figured it out.
if you hold back your convoy in the city its stoped at, say to make goods changes or pick up/sell something if your over loaded.
it seems to interupt the convoys time table and it will make it skip citys to catch up to were its supposed to go next to be on time.
then it compleats the route. 
P3 didnt do this,P3 just resumed the route.
Playing on normal my 1st time through.
would the port being frozen change the route on the map permanetly?
I may have not kept watch on it for long enough and it would have changed back when the port thawed.
Any Help would be welcome.
Sorry i dont know any german.
Thanks That will hepl me out a lot setting up my 1st couple convoys.till i get a handle on what changes will have to be made when i get my own production going.
And keeps me from haveing to learn German.
