How can I stop Dropbox syncing when tethering to a mobile hotspot? (Mac desktop)

I travel frequently and since most of the time phone tethering is not unlimited, I don't want Dropbox to sync over a hotspot. It seems that Dropbox has no functionality to detect this and stop syncing (on the Mac desktop client). How can I make sure Dropbox doesn't suck up my bandwidth when I'm on a hotspot? "Just remember to pause it when hotspot connects" is error-prone because it relies on remembering, and if I forget, I could lose a lot of the monthly data on my cell plan. I just want to automate this.