Although security plans are shutting down while UPS is coming into play.

Are both HA nodes attached to that UPS system?

Both are connected UPS system.

Hi Ismail,

Thank you for reaching out to Sophos Community.

Kindly test the voltage capacity to see if it’s sufficient for all your connected devices.

Try to isolate the devices connected to your UPS or much better test the Sophos Firewall only in your UPS if applicable.

We have previously tested whether the voltage capacity values ​​are sufficient. Unfortunately, we do not have the chance to just test the firewall. The primary firewall does not turn off when there is a power outage.

Are you speaking of the primary node of your HA pair?

Or is this a differnet firewall system?

For primary node. Not a different fw system. When there is a power outage, the auxiliary firewalls are disconnected. It is in passive mode but our internet access is disconnected.

Are you sure, that the second (auxiliary) firewall node is correctly cabled?

Maybe there is an uplink device (modem/router/some active fiber transceiver or so) in the path, that has to be powered from the UPS as well?

Yes there is a modem. They are also connected to the UPS line.

Hello Ismail,

I think you have to investigate your cabling further. There is no way for the second firewall to "know" that the UPS is running on battery, or did you cable the USB signalling cable to one of the USB ports of the firewall(s)?