A reboot of the S9 always brings everything back to life and it could be days/weeks before it happens again but it only happens to 1 of my 3 S9's.
The simple fix would be to just set up a script to reboot that miner once a day as long as that miner never craps out less than a day after reboot. (so you won't have any long downtime)
If it is dying more than once a day you need a real fix on the hardware
Good idea. It's never happened sooner that say 3-4 days apart and will usually go for more than a week without issue.