Deploy 3 Edge Gateway in Sync-failover and sync-only Device Group

Hello,

I've designed to implement 3 EGW device; 1 HA-pair in main site, 1 standalone in DR site, both connecting via private link.

I'd like to synchronize the configuration to all devices, so how to configure in device group, folder functionality? i.e. sync-failover, sync-only.

What I configured but dose not work is put 1HA-pair into 1 sync-failover device group and all 3 devices into sync-only group, for sync-failover group it sync to each other properly but sync-only group did not sync especially on stanalone box.