I have the dumbest problem that has me perplexed.
SRV1 is the FTP server I'm trying to connect too... from inside my work network (CPU1) SRV2 is ftp.secureftp-test.com (random ftp server that I found, just to verify my computer can FTP out). CPU1 is a couple computers inside my work network. CPU2 is a computer outside of my work network.
I can connect to SRV1&2 from outside the network (CPU2). I know that the servers, users and passwords work on both servers from CPU2. I can connect to SRV2 (ftp.test) from inside my work network (multiple computers, multiple public IPs), but I can't connect to SRV1 (ISP hosted ftp server).
Firewall shouldn't be an issue, I can FTP out to SRV2 (as well as other servers). DNS isn't an issue (everything resolves correctly: I can view website on the same server).
Where can I go to troubleshoot this further? It's not a huge issue (workarounds already in place), but I just can't stand an unanswered riddle.