I downloaded filezilla and got similar results. I didn't think the issue was winscp; I was hoping someone might have a pretty good guess at what firewall rule or port forwarding I'm missing that would give these symptoms.

This does not look like WinSCP issue. Or do you have better results with any other FTP client?

I'm using V5.17.7 on a windows 10. Around 3 weeks ago my local computers, those with the same public IP to the FTP server, have been unable to connect neither by script or GUI for no noticeable reason. Offsite PCs like mine connect no issues. Also the server itself can navigate to 10.1.10.4:21. I believe something about that is the issue since I connect to public IP on my PC while locally those PCs try to connect to 10.1.10.4. Also the PCs aren't on that network with the server directly, they're on 10.20.255.xxx..From my comcast modem, I have an aerohive router for the local PCs while the server is sitting on the modem. From the local PC I can ping the server 1ms and sometimes, if I check the FTP sessions in IIS, I do see it connecting and veryy slowly cycling through the commands to connect but eventually times out.
Which is reflected in the winscp log https://pastebin.com/WcDKNdUA
Increasing WinSCP timeout helps the PC get farther before failing but never is able to list the directory.
In IIS, I created another FTP site with different ports and again I can only connect offsite not locally.
In the help articles I found where this cmd might help netsh advfirewall set global StatefulFTP disable but it didn't.