Trunk between Fortigate and Cisco Router

Hi Guys,

I have an issue which I am working on. I have a scenario setup with 2 separate network EG Network A and Network B. Network A is an existing production environment with simple setup. Cisco Router Interface A connected to WAN (OSPF) and Interface B connected to layer 2 switch. Router gives out IP to clients connected to switch with 192.168.2.x/24 IP range. This is working fine.

Network B - Has FG as edge with Interface running VLANS and connected different subnets. EG Port1 has VLAN10 etc with IP 10.11.15.33/28. Port 2 has an IP in the range of Network A on /24 configured configured on the interface itself e.g. 192.168.2.200 (I also tried to put it as a VLAN with subinterface IP as above)

FG is connected to a Layer 2 switch that has VLAN trunk allowed all and e.g port 4-8 is given access as VLAN10. Access port is connected to HOST A, B with IP's 10.11.15.34 and .35 respectively.

I need to have Client from Network A able to access HOST A in Network B which I am not able to do. I can Ping all interfaces in FG and VLANS talk to each other. Issue is when it goes to Network B

I tried different variation - I made a Trunk between the 2 switches and added sub interfaces in the Router in Network A with all VLANS. Router is trunked to Switch in Network A and there is second trunk going to switch  Network B.

I am not sure what I am missing but I am figuring it has to do with port 2 interface in with IP of second network. I am able to ping from FG to the Router using this setup but not to client.

Any suggestions?