Ping utility here (called from the CLI) on aminet:
Ping.lhaAre you able to connect to the Internet with your Amiga?
I use Miami and
SimpleFTP which works great. I am not familiar with AmiTCP.
I run IIS on a PC that hosts an internal FTP site. Ensure you configure user name and password correctly, and open Port 21 on the Firewall on the PC (for the internal LAN), if it is in use.
To keep things simple I run my network behind a router, and assign the FTP server a static IP address.