JavaScript模数没有正确递增变量值

Could someone lend some advice here. I've written this script that is supposed to display max connections and current connections. When you add an additional connection, the maxDevice variable will get an additional 3, so if 3 out of 3 connections have been used, the next connection, 4 out of 3 would instead be displayed as 4 out of 6. Should the user reach 6 out of 6 and then go to 7 out of 6, the output would then change to 7 out of 9, as the max connection would again have 3 added to it, and continue on till infinity.Could someone lend some advice here. I've writt