OK a quick update on this. The customer just got back to me and it looks like the two devices are still syncing... Well the standby device is anyway. Any further thoughts would be well received...
Time to get Astaro Support involved. Just out of curiosity, you might look at the High Availability log. I've seen a situation where the MTUs of the sync interface became mismatched in an Up2Date, but that needs to be fixed at the command line.
Cheers - Bob
Sophos UTM Community Moderator Sophos Certified Architect - UTM Sophos Certified Engineer - XG Gold Solution Partner since 2005
Updating won't fix this problem if it's the MTUs that aren't matching. If you know how, you can check that on each 220 with ifconfig. If not, then you should ask your reseller to open a Support ticket with Sophos/Astaro.
Sophos UTM Community Moderator Sophos Certified Architect - UTM Sophos Certified Engineer - XG Gold Solution Partner since 2005