Don't use fully automatic trading. (the button on the left)
Every wagon will see the same city as needing transport which means if it is far away every wagon will head to that city following each other around like lemmings, when one will do
Assign individual trades per wagon/ship. (the button 3 or 4 to the right, brings up annoying large list)
note assigning 1 wagon per good with multiple cities, works better than assigning 1 wagon to a specific city pair with multiple goods
If the Route is important assign one vessel to it full time. (for example getting ore to your ironworks if you can't produce enough in one city)
Every wagon will see the same city as needing transport which means if it is far away every wagon will head to that city following each other around like lemmings, when one will do
Assign individual trades per wagon/ship. (the button 3 or 4 to the right, brings up annoying large list)
note assigning 1 wagon per good with multiple cities, works better than assigning 1 wagon to a specific city pair with multiple goods
If the Route is important assign one vessel to it full time. (for example getting ore to your ironworks if you can't produce enough in one city)