Windows FTP Sanity Check: "Transfer Channel can't be opened."

I am running Windows Server 2016 and have two FTP sites setup in IIS (one using port 21 and one using 21000). Both aren't working for me and I need a sanity check to get these working today.

It's not networking because I can successfully Telnet into the Server on those Ports. I have been over permissions a dozen times, comparing exactly what's in Production (what I know works) with what is on this STAGE server, but it still seems like that's an issue (based on the status codes below).

I'm stumped as to a next level of troubleshooting. I even recreated the FTP site in IIS from the ground-up and am still getting the same results.

This is the error I'm receiving:

Transfer channel can't be opened. Reason: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.
Could not retrieve directory listing
Data channel timed out.

Both the local logs and server logs jump from "227" ("Entering Passive Mode") to "550" with "Data Channel Timed out" ("Requested action not taken. File unavailable (e.g., file not found, no access)").

Thanks in advance for your help.