Hubitat needs the local time to be correct for various local services to work (eg. time-based Automations). It currently uses a hardwired, Internet-required, Time service (eg.
pool.ntp.org on a C5) to get this information (initially, upon boot) and refresh/update it over time (for drift)
As an alternative, it's provided a manual over-ride, allowing a user to set the time based upon the Browser's time.
Hubitat doesn't have a battery backup for it's RTC, so if Hubitat goes offline whilst it's disconnected from the Internet (eg. it's intentionally standalone) then the time will be lost and certain automations either may not occur, or may not occur at the expected time)
There are a number of discussions that are all rooted in issues with the NTP that's required to get time in sync. They're not all related to the disconnected use-case, but they're all indicating how sensitive the device is to it's environment, esp when NTP may be blocked (eg. by the ISP).
Here are a sample:
- Hubitat hub if disconnected from internet …
- Setting system time
- Update Failed, Please Try Again on brand new hub
- Cloud Connection Unavailable / Time incorrect
- Please Help Me Find Out Why Things Simply Stop Working?
- Red flag in upper right corner
- Hubitat hub - Excessive calls to NTP services
- Offline Hub cannot keep accurate date time
Formally add the ability to over-ride the time server (host, port) that's used by Hubitat (so it can truly be detached)
- a) Provide an end-user settable (persisted) config that specifies the NTP Server to use.
- b) Observe the DHCP Option 42 (NTP Server) settings, as an override for (a).
Ths setting is currently requested during Hubitat's boot/DHCP cycle, but the DHCP NTP-Server response is ignored. I have mine set to use my Router, where I can configure how to source the information.
- c) If neither of the above it set, fallback to the current default (
With these in place you'll provide users, with tricky and/or disconnected operating environments, with a way to (automatically) setup the time in all the correct places.
Ref(s): [Bug]: Hubitat's explicit use of Google DNS (188.8.131.52) for similar DNS-based hard-coding.