Homeassistant Failsafes, reduncancy

Would like to know what people have as a failsafe in case HA fails. or for example the MQTT broker fails.
I did look into setting up a HAPROXY for the MQTT broker (I did have MQTT servers running on openwrt on BT hub routers) I have now moved that to docker. I think my paranoia comes from the MQTT that used to be part of Homeassistant that I was running on a Raspberry Pi 2 would just stop working. I do have 2 instances of Homeassistant running at the same time the difference is that one instance is pointing at the IP of a MQTT broker that the sonoff devices are not looking at, if something fails I just have to change the MQTT server in the sonoff setups.

Failsafe is manual operation

Honestly is as reliable as Electricity in my home.
HA only not work when electricity out. In the case nothing to do but manual operation

I have a standby HA instance, and a standby MQTT instance. I don’t change the MQTT server in the Tasmota’s (and Zigbee2MQTT, espRfLink, …), just change the ip-adress for the MQTT server if it fails.

Are these on different host server?

Yes they are.

Failsafe by design.

I am using HA primarily for monitoring and notification, and to add/improve functionality to already existing systems.

All my lighting systems will function normally if HA goes down, as will environmental monitoring devices, security system, surveillance cameras, garage doors, etc.

An example. I have a 433mhz remote control in the car that will run an automation. It detects if anything except garage doors will prevent the alarm from arming (warning if it does), and if not it closes all open garage doors and arms the alarm, then turns off the lights in bedrooms. The doors/alarm can be controlled using keypads/buttons, and by the alarm system keyfob, and by separate applications that do not route through HA if needed. It is just far more convenient to press 1 button and be done, but I do not loose critical functionality without it.

Might not work in you case, but I check if certain sensors that I update via MQTT have recent timestamp. Here is the automation:

- id: cyberspace_mqtt_publish_checkl
  alias: CyberSpace - MQTT Publish Check
  - platform: time_pattern
    minutes: /5
    seconds: 0
  - condition: template
    value_template: '{{ (as_timestamp(now())-as_timestamp(states.sensor.bijkeuken_luchtvochtigheid.last_changed))
      > 900 }}'
  - service: notify.matthijs
      message: Time stamp of most recent MQTT message is over 300 seconds, please
        check MQTT connections!
      title: MQTT Error
        priority: 0
        sound: incoming