Problem with F180 ARP-NAT

Good day everyone,
I Have a problem with Cambium F180 Forwarding traffic through e505 link, I’ve tested the connection in the lab and it works fine while I’m directly connected to my Mikrotik router same LAN.
But when I test it through l2tp VPN it doesn’t work as expected, the traffic is passing normally through the tunnel I can reach the F180 but I can’t reach the e505 from my computer even though I can ping it from my router Mikrotik, I think the problem is the link between e505 and f180 ARP-NAT not forwarding my packets,
please look at the picture below so you can have a better understanding.