We had an outside customer recently migrate their FTPs server and we've recently been experiencing an occasional "REPLY: 425 Cannot allocate local port". The customer responded with "Do you have the data port range allowed through your firewall of 2030-2130?". I had out network folks allow that, but we're still having the same issue. The resource in MFT is setup as a pretty standard FTPs connection using port 21 and PASV mode enabled. If anyone has experienced similar challenges, any assistance or suggestions would be appreciated.

Dan,

By default, GAS will utilize the Passive Port range of 30000-32000. Opening up the 2030-2130 (I would assume) would only affect the passive port range on THEIR server, if that's what they use.

During negotiation, GAS will tell their server to utilize port xxxxx (within the range mentioned above) to start communication (Data Transfer).

If you're connecting to THEIR server, then the issue might be that their Passive Port range isn't opened for them (Their Local) not yours. As a client, you don't have say-so as to which Passive port to connect to. That happens during the handshaking. As long as your client allows you to connect to them, you should be fine.