Please see the attached image.
We need to set up a secure VPN connection between MikroTik 1 and Mikrotik 2 devices and direct all the traffic from PCs through MikroTik 2 router (including internet traffic). MikroTik 2 is configured as SSTP server. Everything works as expected in situation 2, but if MikroTik 1 is behind another NAT PCs cannot access the internet despite the fact that MikroTik 1 successfully connects to VPN, and traffic is passing (I can ping Mikrotik 2 internal VPN IP from all the pcs).