Active Sync Stopped Working?

At the end of December, I noticed that a few of my domains had not received emails through the default Mail app on iPhone (added via Microsoft Exchange). I checked the Roundcube web mail and all emails were still there and being delivered, just not showing on my iOS devices.

After removing and adding the accounts again, the account added with green ticks next to information, but no emails would come through.

I then added the account again via the configuration link, and that pulled through all my emails for a few days - then the same again, emails stopped coming through.

I was on v66 for the start of these issues, but have since upgraded to v67 in hopes that the issue would be resolved, but it has not.

Could anyone assist with this issue?

Thanks!

Have you checked the Z-Push error logs?

Edit: The logs are under /var/log/z-push/