Is there a way to have a smartplug turn on if I lose connection at home? I have it set up to run a macro to send me a notification if the hub goes online and to activate my mobile hotspot so the hub can run off of it. I have a mini router that is plugged into the hub and is powered by a smartplug.
Sure, this is a very common request and there are already eight or nine threads in the forum about it.
You just can’t do it with anything involving smartthings. 
that’s because it would require custom code and all custom code runs in the cloud.
Instead, there are a number of different smart plugs sold for exactly this purpose. Most of them are Wi-Fi and ping a specific website at regular intervals. If they don’t get through to that website, then they reboot themselves. Very simple and works well.
See the following thread:
Just thought of something, the smartplug I’m using is not connected thru smartthings, but thru the smartlife app and alexa