Head Office      :  (Real Ip: 182.168.99.180, Local Ip: 192.168.60.0/24, Gateway: 192.168.60.1)

Branch Office   :  (Real Ip: 202.4.125.225, Local Ip: 192.168.60.0/24, Gateway: 192.168.60.2)

Step 1: Interfaces>GRE Tunnel> Type (Name & Remote Address IP(Real IP)) .

Note: Remote address where you connected.

Step 2: IP> Address > Type(Same Block IP and Interface (Select The Name))

Step 3: IP> Routes > Type ( Remote Local IP(Branch Office) and Getway (Branch Office))

Note : Same Configuration Both Side.