Unable to connect via FTP Remotely

I have a basic Western Digital MyCloud setup at home. I mostly utilize Panic’s Mac and iOS “Transmit” Application to FTP files into it both locally and while I’m away with their iOS application.

Using Infuse 4 or Infuse 5 on my iPhone, I can’t seem to connect to it remotely. If I use Transmit on my phone, it can connect flawlessly, so I’m led to believe this isn’t an issue with my configuration.

In Infuse 5 I’ll go to “+ Add Files”, select “via Network Share” (as the “via FTP” option only accesses an FTP server over WiFi), Give it a name, my external IP Address, credentials, and change “Protocol” to “FTP”. I use the same old “21” port. It always seems to time out.

On a side note, if I use Infuse 5 on my iPhone to connection via FTP (Same steps as above but give it my Western Digital MyCloud’s Local IP) it seems to work flawlessly. My issue is only when I’m trying to connect remotely. Any suggestions?