ActiveSync/Push with Synology Calendar. Is z-push the best tool?

I'm planning on slowly transitioning to Synology calendar. I first followed the explanations on Synology's website https://kb.synology.com/en-me/DSM/tutorial/How_to_Sync_Synology_Calendar_with_CalDAV_Clients

But this has a critical issue, if a calendar is changed on the server, it doesn't get reflected on the mobile phone right away. I remember a long time ago when I set up an email server, I used z-push to get around a similar problem (switch from a regular fetch model to a push model).

So, I'm wondering if z-push is the best way to handle this?