My synology nas emails me every time it is down and every time Amazon or Comcast are down.
Last I checked, Amazon had the fewest 9s of the three (going back a few years...)
Dont break their delusions that "the cloud" is the prefect place were there is no down time, no security issues...
If you pay enough money to run things on their computers all problems are solved. it is only when you self host that is the problem :)
If does go down then it's not cloud, no matter what hardware you're using.
In general, my rule of thumb is: what's the upper limit, the capacity or your wallet?
If the limit is the capacity, then it's HA.
If the limit is your wallet, then it's cloud.