FTP Upload

Dennis_M wrote:

I moved over to T-Mobile Home Internet about 2 months ago.  I use winscp, filezilla and terminal regularly in maintenance of several web sites.  WinSCP and filezilla had worked fine for me until this weekend when directory listing mostly appeared to time out and any file edit/saves (say via winscp) failed as well. This had been working without issue, so something in my 5G coverage has to have changed.  Very frustrating! I found Guardian61's post above and using a VPN resolved the issue for me, though likely for a different reason (NAT/Port Map/IP duration). FTP is a TCP based service exclusively. There is no UDP component to FTP.

I'm still wondering what happened and why and have a ticket open with T-Mobile.  As a test to see if possibly something had changed in the site hosting environment or on my laptop I hopped over to a coffee shop and exercised both filezilla and winscp using my existing configurations.  The ftp services worked as expected (without VPN) and indicate no change in the endpoints, that leaves the network.

The problem is T-Mobile. As a leading edge company it uses !PV4 over IPV6. It does not do IPV4 natively and maps IPV4 over IPV6. For many things this is transparent and works fine, but for FTP the ports change. Because of that an error occurs saying the data coming back is not on the same port it was sent. A VPN resolves the issue. I paid $85 for two years for a VPN that works for me.