By default, without any changes to services-start, the port forward is configured to access the router's GUI on the *LAN* side, NOT the WAN side. So the WAN's firewall is irrelevant. You should have at least been able to see your router's GUI come up and even login if you wanted to, just as if you had attempted to login to the GUI from any wired or wireless client on the LAN. Are you saying this didn't work?
Remember too, you have to use the VPN's external IP and the PIA assigned external port (NOT the internal port you specified in services-start) to reach the internal ip and internal port specified in services-start, and do it from outside the WAN of your router, perhaps on a smartphone, neighbor's wifi, etc.
The script publishes the VPN's external IP and PIA assigned external port at http://<router-lan-ip>/user/pia/ext_port_forward.html
Yes, there are a lot of echos, and some of them are intended to report what the router is doing, like indicating the external port if it was successfully opened. You can examine anything the script writes to the syslog by executing the following command from a shell (ssh).
Code:
cat /var/syslog.log | grep merlin-pia
And how did you check this? If that was through the WAN, it's going to see the WAN's public IP and report closed. It's only going to work if the request is made though the VPN tunnel so it sees the VPN's public IP.
Regardless what it reports, all that matters is if indeed you can access your NAS over the tunnel using the VPN's public IP and PIA assigned external port. Also, the ip (--ip) in the services-start script has to be changed to the internal IP of the NAS. I assume you did this too, but you only specifically mentioned changing the internal port (--port).
This gets a bit tricky because you have to keep in your mind the difference between what is specified in the services-start script (which are the *internal* ip and port of the port forward), vs. the *external* public IP and assigned PIA port. You use the latter (from say your smartphone on the cellular network) to gain access to the VPN provider's end of the tunnel, which then works it way over the tunnel to be forwarded by the former at the OpenVPN client.
So let's say the VPN public IP is 199.199.199.199 and PIA assigned external port is 55555, and the services-start ip is 192.168.1.100 and port is 1194, on your smartphone, you specify the following.
Code:
http://199.199.199.199:55555