Issue with a WireGuard server behind FortiGate

Hi,

I'm having issue to access to a Mikrotik router, that is a WireGuard server, behind a FortiGate 60F.

IP of 60F is 192.168.113.1, the IP of the Mikrotik is 192.168.113.4, the WireGuard port is 51820, I created a virtual IP on the FG

SYSFW60F (WireGuard) # show config firewall vip     edit "WireGuard"         set uuid f03ef9d2-b285-51ed-108d-f7e3e193c54a         set extip xx.xx.xx.xx         set mappedip "192.168.113.4"         set extintf "wan1"         set portforward enable         set protocol udp         set extport 51820         set mappedport 51820     next end

Then a firewall rule with the virtual IP

SYSFW60F (2) # show config firewall policy     edit 2         set name "WireGuard"         set uuid e023f12c-b1ce-51ed-67ea-7da8d93cead2         set srcintf "wan1"         set dstintf "internal"         set action accept         set srcaddr "all"         set dstaddr "WireGuard"         set schedule "always"         set service "ALL"         set logtraffic all         set nat enable     next end

But I don't see any traffic using this rule, nor I'm able to get the WireGuard handshake.

Any suggestion? 

Thanks