This has been happening now for several months. The issue comes and goes on it’s own.
Sometimes I’ll receive an Alexa announcement that “xxx is not responding”. When this happens I open the SmartThings app and all of the Lutron switches are offline.
I’ve had this setup with no material changes in the last (2) years
The Lutron devices show offline in SmartThings app and the SmartThings WebUI
I can control the lights, etc from the Lutron App without any trouble.
The SmartThings and Lutron hubs are on wired ethernet connections.
I have 1gig ATT fiber and no other internet issues that correlate.