Very interesting... We also have a similar issue. We are adding an MX 67 on our spokes that goes over AutoVPN to our DC and it only happened a few times in the beginning, but now with every migration of adding an MX 67 to a spoke for SD-WAN, we need to reboot our MX.  We are also connecting to a Fritzbox and most of the time it is the 7590. We just passed the 100 mark for migrations, but our issue is with the CAP WAP traffic of Cisco AP's that do not want to show up on WLC (Flex Connect) and the only option at the moment to fix this is to reboot MX then it is fixed.  We do have an open case with Meraki and they have no clue why it is, but we can see that the UDP port is changed when it comes back to the spoke. I am going to check the firmware of the Fritzbox and see if this is related.  ... View more