Failed to perform SSL handshake

We had a power outage and the backup generator came on.

Now weather on my wifi LAN or cell service - nabu casa is giving an error

Failed to perform SSL handshake.

maybe your HA is offline?
I got that message when HA is not running.

I was thinking that a system that runs locally couldn’t be offline I’d the power is up and running. What am I missing?

The power being up is not a guarantee that your HA box is UP. Did the power cut cut power to HA before the generator picked up? Did the switch surge the line? Is the generator power clean enough to drive a pc/Pi/NAS whatever?

The power dropped for ~30 seconds before the generator fired up.

I’m not sure what you mean re:clean enough to drive a pc/Pi/NAS

Not all power sources are built the same…

Basically unless a generator is built to put out ‘clean power’ it’s probably putting out a really nasty square wave power profile. Short version… Running some lights at a campsite. No problem… Hi tech gear doesn’t like it much and in the case of UPSs and some power supplies they cut in/out surge etc.

This is a generac whole house with 24kw.

Great! Generac makes great year (it doesn’t completely eliminate the possibility but you should still review the generator docs and what general says about the output waveform, any cautions they give and what the manual says about clean power…)
That said, it still doesn’t take away the fact that the fact the generator is running doesn’t automatically mean your HA box c
is up. There’s a lot that can happen in thirty seconds m my guess is the box didn’t boot correctly from the bounce on the power cut. Will be interesting to know once you can look. If. That’s the case put a very small UPS on the box to cover the power switch.

Could you define UPS switch?

What i was talking about was the act of switching. As you’ve already said it takes about 30 seconds for your (i assume automatic transfer switch) load detection to kick in, recognize the need to start the generator and hit the automatic transfer switch… Something like this - Back-UPS | APC USA

Dropping a power line isn’t easy on your computers in the best of circumstances nor is the startup current coming out of some generators. - the generator covers your own power until the grid returns. If you’re not already on whole home battery then you want something on the outlet to support the device so it doesn’t drop until the generator kicks in. You also don’t know how many times the power ‘blipped’ before it actually went out…