Unsuccessful with opening port using service

Port forwarding is in general easy and reliable. Permitting the router WAN/Internet interface does have a public IP route-able address, the ISP does not have any restrictions like software firewalling.

Does the router Internet/WAN port show as using the same public IP address like your DDNS provider does point to?

Could there be probably -two- or more NAT routers in the data path, like an ISP modem-router plus the Netgear router?

More difficult, as you talk of an FTP service, for most non-IT network admins, this can proof to be a can of worms to the new network admin. Not all ftp clients can be configured easily to behave like the user expect - and more the FTP protocol suite - does require. Real FTP does consist of two concurrent connections (and ports), one for ftp-control, and one for ftp-data 

If desperately have to use FTP, start with an ftp client offering good insight of what is going on on the connection attempt, like FileZilla 

And seriously, most problems are not related just to port forwarding (port open on the router), but are related to the idea of let's use ftp - as it does sound simple. Alone real FTP does not just work on a single port like 49152/TCP - but it's certainly a starting point, and you don't have to use the default ftp-control port.

To cause more confusion, FTP can be implemented also using SFTP (SSH protocol based - unless Microsoft extended the capabilities recently, Windows does not provide support for this), and FTPS (better FTPES).

What service, what server (hey, I've seen you talk of your PC, likely Windows) you intend to operate, and what clients, and what user base you intend to be workable for this "FTP" connection?