After firmware upgrade from v.19 to v.20, HA failed to work and currently we are running on one FW.
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Important note about SSL VPN compatibility for 20.0 MR1 with EoL SFOS versions and UTM9 OS. Learn more in the release notes.
I have upgraded a few firewalls from V19 to V20 and did not have any problems so far.
What have you tried already to fix it?
Managing several Sophos firewalls both at work and at some home locations, dedicated to continuously improve IT-security and feeling well helping others with their IT-security challenges.