Cannot upload/download files using ftp

[ChasDROID]

T-Mobile - Galaxy S4

I am able to upload and download files from my server using an Android ftp app on my phone when on my home WiFi

However I am unable to do so when using 4G or 4G LTE
The ftp app goes as far as "AUTH TLS OK." then just freezes

I'm using the AndFTP app but also tried several other ftp programs from the Google app store all with the same results.

Have only had T-mobile for a month.
All was ok when I was on Sprint and I was able to upload/download.

Anyone have experience in this area ?

Thanks

 

[Tall Mike 2145]

I've had no issues connecting to FTP or SFTP, nor have I had any issues using SSH to access servers remotely. Hmm...

 

[Sicily1918]

Are you making sure to have a separate entry for being 'outside' your home? E.g., I SFTP to 192.168.1.10, but that won't do me any good outside of my specific home network.