On the FTP configuration page, in the Hostname field, add the port port number after the hostname (preceded by a space).
Hostname: myhost.com 2121
Article ID: 131
Last updated: 11 Jun, 2020
Revision: 1
PRODUCT SUPPORT -> IP Cameras & Video Servers -> NetCam XL -> FAQ -> How do I specify an alternate FTP port. https://stardot.makekb.com/entry/131/