OPNSense site-to-site OpenVPN client-server

[adispy]

Hi everyone,
I have been using this amazing product for quite some time and now I got in a bit of an issue and can't seem to figure it out, and maybe someone can help me out here.

I have two OPNsense VMs in different locations with a site-to-site OpenVPN, or at least this is what I am trying to achieve.
The VM in the main site (A) is running as server and the one in the other site (B) is running as client. They are connected and traffic is flowing from site B to site A (after I add proper routes to clients), but the other way around is not working at all.
It needs to run in client mode in site B because I don't have access to the client router yet so I can port forward and do IPSec.

I looked at the routes and they seem fine, and I also created routes in site A on some of my clients to send the traffic to the OPSense server for the remote site B subnet but I can't seem to make it work.

Maybe I misunderstood the concept and you can't create site-to-site in a client-server configuration.

Any idea will be much appreciated,
Adrian