Why are there Hub outages with 2.0 Hubs

What we thought we were going to get with regards to local processing in V2 and what we actually got were two very different things.

At the present time, only a very few things can run locally: basically the official smart lighting automations, a tiny bit of SHM, and those only if the devices being used are also eligible to run locally.

Many things are still dependent on the cloud, including routines, any use of Phillips hue bulbs, all notifications, all locks, the mobile app itself, Etc.

Details in the following thread

SmartThings is a highly flexible and versatile platform, but it is still mostly cloud dependent.