For the last 2-3 weeks we have been having intermittent flapping of connectivity within our Meraki AutoVPN network. We have 4 offices in a mesh topology. The event logs on our MX firewall would show entries for 'VPN Tunnel Connectivity Change' and 'connectivity: false' while specifying the peer losing connectivity. It seemed to happen on the hour, and last about 5 minutes. Ping attempts during that time would timeout between offices. However, normal internet access was not affected - only the VPN tunnels. So what was the cause? After working with a couple of engineers at Meraki support, some suggested firmware upgrades and rollbacks (to no avail), we requested an escalation of the issue. After some analysis on their end, they discovered that the VPN Registry servers we were using were very busy. They changed our primary and secondary VPN registry servers. Since then, no more issues. Hoping this post will save someone some time in the future.
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