Guessing the battery died and the clock reset throwing off a https parameter. Happens to my daughter's tablet when she forgets to charge it and then she can't connect to https sites without resetting the clock.
Why on earth is this answer downvoted? I'm pretty sure clock resets can cause HTTPS problems (even though they are unlikely to be in the OP's case, it being a server).
And if you disagree, please explain...so that we can all learn and understand.
Raid battery has nothing to do with the clock. Even the motherboard battery affects the clock only when the machine is turned off. Normal systems connected to the internet will sync to NTP both at boot time and continuously afterwards anyway.
Also the server time doesn't matter for TLS. It's the client that has to verify the certificate validity. (https://tools.ietf.org/html/rfc5246.html#section-7.4.1.2 "Clocks are not required to be set correctly by the basic TLS protocol")
So no, raid battery should have nothing to do with the system clock.
This has popped up a couple of times and I never got around to confirming either way. I always went to the trouble of syncing to rule it out before moving on. (sometimes annoying on an isolated test network)
Thanks for taking the time to link the relevant section of the RFC. I'll remember this next time (or at least know where to check quickly ;) )
1. These things would still have AC power. The battery is more like a UPS battery - the only way for clock reset to happen is for both external and battery power to fail, at which point it will die from lack of power anyhow.
2. The clock on the server wouldn't have anything to do with the RAID array. If I disconnect a hard drive, my motherboard still gets along fine.
And if you disagree, please explain...so that we can all learn and understand.