Disagree. If it is D box problem,

the system will not work no matter the weather dry or wet. Since the system works when it is dry and not work when wet, it is due to the drain field can not take too much water when wet. Also too many people use water. Over the capacity of the system. Good to check D box. But I bet there is no problem there. Need to expand the drain field if too many people use water. 2 to 3 k will be good price.