http://help.vaultpress.com/connection-issues/
My guess is that the VaultPress API Server is making HEAD Requests to check if your site is up/reachable or not. Try allowing HEAD Requests first: http://forum.ait-pro.com/forums/topic/jetpack-site-uptime-monitor-403-error/#post-15400 If that does not work then maybe whitelisting the IP CIDR Block or User Agent would be needed.
- This reply was modified 12 hours, 51 minutes ago by AITpro Admin.