Would This Solution Work?
I don't know if anyone suggested this before and I don't know if this will work, but I hope this idea might work.
When the a clan "loses connection" during a battle over a certain amount of times, the opposing clan may choose the end the war. The clan that ends the war may collect their bonus loot, while the clan that keeps on "losing connection" would not receive any in return.
I understand that people will still be able to do what they want, but this will limit the number of times. Just an idea.