If local execution doesn’t matter, try my DTH and set the checkin interval to something like 15 minutes to see if that solves the problem.
If you’ve been using my DTH for a while and it’s been a while since you’ve updated the settings you should do that because I’ve made some changes that won’t get applied until the settings are updated.
All custom DTHs prevent the device from running locally, but not all of the default DTHs run locally either. The default DTH for Aeon Siren does run locally, but only if you’re using the device with SHM or Smart Lighting.
The device unavailable problem and almost every other issue you’ll encounter is caused by SmartThings and is not the manufacturer’s fault.
The reason this is a common problem with Sirens and not your other devices is that they’re rarely used and they don’t sleep which means they don’t automatically check in with SmartThings at a regular interval.
Other non-sleeping devices like outlets usually report values like power or energy on a regular interval.
The default Aeon DTH relies on the SmartThings device-watch to ping the device, but it often doesn’t wait long enough for a response or doesn’t ping it at all. They’ve fixed a lot of the bugs with the Health Check feature so it’s a lot better than it was, but it’s still not perfect.
My DTH for the siren self polls using a schedule which is why it doesn’t/shouldn’t have the device unavailable problem.