what is this HA info page telling me?
HA is green and the peer is faulty. Does it mean, the peer is alive but unhealty or does it mean, peer is dead?
You have a dead peer. I am sure you have tried to reboot, but I think you may need to break HA, check the 'dead' peer can still boot successfully, then re-establish HA
Faulty status is described…
You could start to investigate this: https://support.sophos.com/support/s/article/KB-000035558?language=en_US
Sometimes, the HA Daemon tells you faulty, but the device is still accessible via SSH:
Thanks. I can confirm, the peer is dead. LEDs are off.
Nevertheless the machines dashboard shows everything good except interfaces -> HA NIC no link.
No hint for a problem with the cluster. I don't think this is what we want.
Update: after the 2nd machine was put back into operation, the only thing I could find different was a tiny (M) on the dashboard:
From the documentation: