Hello!
I have a Fortigate 60F, with 234Fs, one as Main AP and the other one as Leaf via mesh.
On a job site with existing mikrotiks metal 52ac and devices connected via NIC, I'm having high ping times (and regular time-outs) from the server to the Clients with Mikrotiks, but If pinging from the Client to the server there are no timeouts. All clients use static IPs. Also, I recently discovered that a bullet M5 works with no problems. I don't know what could be causing this issue... Welp!
Maybe if you provide some meaningful details someone may know, with what you posted (almost nothing) it could be anything (and the contrary of it).
A scheme of the network, the configurations of the involved Mikrotik devices and detailed description of what happens and on which connections it happens are the bare minimum to allow anyone to be able to provide suggestions.
Generally speaking, when things work in one direction but not in the other the issue can be firewall, nat or routes, but it could also be settings on the server or something else.
Right now you are in the "I'm ill, doctor. Help!" situation:
https://jdebp.uk/FGA/problem-report-standard-litany.html