Maybe one of your MX is behind a router? I have seen that before. ... View more

I would start from checking the pings between your sites. See what is the time in ms? After that I would check Group Policy and Traffic Shaping to make sure that everything is setup correctly Check also Site-to-site outbound firewall and Site-to-site inbound firewall   ... View more

I would start from checking settings in Site-to-Site VPN 1). Make sure that you setup Hub (Mesh) 2). Add to local subnets that you want route between sites YES 3). Nat traversal Automatic 4). Go to Non Meraki VPN Peers and Add Peer 5). - Name - VPN Name for example site name where is going to)      - Public IP - IP address of remote site      - Private Subnets - Those are remote subnets that you would like to see over IPsec Tunnel. If you have multiple subnets that you want to go to specify all of them for example 192.168.100.0/24 10.0.10.0/24 10.0.60.0/23     - IPsec Policy you could leave as default but if you want to change something you could do that     - Preshared Secret - Make sure that key match both sites     - Availability - All Networks - or Specify what network should be allowed if you have multiple networks in your organization If you do that you should be able to ping across both sites.             - ... View more