FTP Settings

(a) the NAS is set up on port 21 and you are forwarding to 51000. That's the first mistake.
(b) You haven't forwarded the passive ports - that's the second mistake.

Personally I use a non-standard port like 51000 instead of 21. If you want to do that then
(1) forward 51000 - 51004 in the router to 51000 to 51004 in the NAS
(2)Configure the FTP service to use 51000 for the main port, and 51001 to 51004 for the passive ports
(3) You don't need masquerading if you use filezilla, so leave that disabled.

(4) create an entry in filezilla's site manager for the NAS
-Use the DDNS hostname from dyndns.org and set the port to 51000
-protocol is ftp
-encryption is require explicit FTP over TLS
-logon type is normal
-user/password is your NAS account (can be admin)

(5) you could also go to the transfer tab, and limit the number of connections to 2 (4 will work, but generally I use 2).

(6) Choose "settings" from the edit menu in the filezilla toolbar. Choose "Passive mode" under connection->FTP. Check the option "use the server's IP address instead".

That should work.
-

StephenB - Thank you for your message.

I have tried the settings that you have said but still no joy.

Router Settings
Programme Name Ports (Start-Finish) Protocol Device IP Enabled
Filezilla 51001 - 51010 Both 192.168.1.103 True


ReadyNAS Settings
Enable FTP
Port: 51000
Authentication Mode: User
Allow Upload Resumes: Enabled
Home Shares Over FTP: Disabled
Passive Ports: 51001 - 51010
Use Masquerade Address: Disabled

FileZilla Settings
Host: XXXXXXX.dyndns.org
Port: 51000
Protocol: FTP - File Transfer Protocol
Encryption: Require explicit FTP over TLS
Log on type: Normal

Transfer settings
Passive
Maximum number of connections 2

Error message:
Status: Resolving address of XXXXXXX.dyndns.org
Status: Connecting to xx.xxx.xxx.xxx:51000...
Status: Connection attempt failed with "ECONNREFUSED - Connection refused by server".
Error: Could not connect to server

You didn't forward 51000!

StephenB

I've amended the settings as follows but still no joy

Router Settings
Programme Name Ports (Start-Finish) Protocol Device IP Enabled
Filezilla 51000 - 51010 Both 192.168.1.103 True


ReadyNAS Settings (192.168.1.103)
Enable FTP
Port: 51000
Authentication Mode: User
Allow Upload Resumes: Enabled
Home Shares Over FTP: Disabled
Passive Ports: 51001 - 51010
Use Masquerade Address: Disabled

FileZilla Settings
Host: XXXXXXX.dyndns.org - I have also entered the external public IP address also to test.
Port: 51000
Protocol: FTP - File Transfer Protocol
Encryption: Require explicit FTP over TLS
Log on type: Normal

Transfer settings
Passive
Maximum number of connections 2

Error message:
Status: Resolving address of xxxxxxxx.dyndns.org
Status: Connecting to xx.xxx.xxx.xxx:51000...
Status: Connection attempt failed with "ECONNREFUSED - Connection refused by server".
Error: Could not connect to server

What happens if you connect on your local lan? try both 192.168.1.103 and your ddns name.

Hi Stephen

Connects just fine locally using 192.168.1.103 but it just will not connect externally or internally using the dyndns account or the public ip address. I have tried this using your suggested ports (passive and active) and port 21 (active) and both work locally using the 192.168.1.103 address.

I can ping the dyndns address and the public ip address with no problem.

Thanks

The FTP server needs to be passive, otherwise you won't be able to access the NAS if your client is behind a firewall (even with port forwarding).

It sounds like something isn't right with the Asus port forwarding. Did you delete the original forwarding of 51000 to 21?

...On my router which is a Linksys AC1900 EA6900-ME Port forwarding External Port: 21 Internal Port: 51000

Also try testing with http://www.canyouseeme.org/ and see if 51000-50010 show up open there.

StephenB

Thank you for your continued support. I am pleased to tell you that I have found the cause of the problem.

It was not the Asus or in deed the port forwarding at all. Du, the local telecoms provider had updated the fibre optic cable into the property and in doing so installed a Echolink Gateway GPON Terminal without any discussion whatsoever. Whereas the original installation obviously allowed straight through connections with port forwarding being resolved on the router, the new installation has port forwarding included within the unit and the engineer failed to set it up or advise that the unit had been installed.

I constantly called Du to advise that there was issues after the installation but they refused to accept that there was any issue. That said, they didn't know what ftp was and I had to explain so probably shouldn't be surprised.

Once again thank you for your assistance.