Conflict in roles in HA

Hello Angelo Orlando1,

Thank you for reaching out to the community, it is not mandatory that Active device in HA A-P is master node all the time, so you may check master node with the help of below command - nvram get '#li.master
Furthermore you can refer the HA troubleshooting guide - https://docs.sophos.com/nsg/sophos-firewall/19.0/Help/en-us/webhelp/onlinehelp/HighAvailablityStartupGuide/HATroubleshooting/index.html 
Question: Are not the Sophos Appliances directly connected with each other ? OR there is a switch playing a role between the dedicated HA link ?

For Both the firewalls LAN PORT is under the same switch.

For The dedicated HA link one direct cable (no switch between them).

nvram get '#li.master
Perform the following command on both the appliances if you get yes 
that appliance will be active one !

Hello,

Greetings,

We need to disable STP on switch interfaces to avoid it happening and both the interfaces should be part of same VLAN. Kindly refer to the HA setup guide!

https://docs.sophos.com/nsg/sophos-firewall/19.0/Help/en-us/webhelp/onlinehelp/AdministratorHelp/SystemServices/HighAvailability/HAPrerequisites/index.html#prerequisites

On the primary|master ONLINE it's a YES

On the Auxiliary|slave  OFFLINE it's a NO (currently this is the one having the same ip and mac-address of the primary)

so connected to our switch is not reachable|pingable and results in a mac flapping in the switch logging.

What we do not understand is why the secondary, after the restart, didn't come back on the original slave configuration for ip and mac-address!

Actually we have this configuration in HA with these firewalls XG330 since 4-5 years and lately we didnt change switch or switch configuration.