Autoupgrade to MX16.16 and tunnel doens't work correctly anymore
We have a Fortigate 1200D on 1 side and a cisco meraki MX84 version 14.53 on the other side.
The tunnel works fine now but when we upgrade to 16.16, doesn't work for some parts. The tunnel has status up but traffic from the fortigate is only allowed to 1 vlan of the cisco meraki. There is no firewall policy blocking this traffic.
Because when we start traffic from cisco meraki from another vlan, we can ping from the fortigate to that new vlan.
The RemoteID became mandatory from 15.x and up. For 99% of cases, this will be the IP address configured outside your Fortigate (usually a public IP address, but it could also be a private IP address if the Fortigate is sitting behind something doing NAT).
Also, I think DES got disabled at some stage, in case you have ti configured to use that.