At the risk of sounding dumb, but, there's no page on the official website with older versions.
I can send older versions by email. No problems or bugs with ProScan using the Wi-Fi. If an older version works, that would indicate an Internet Security program exemption was added for an earlier version but not for the latest version.
Since ProScan see's the scanner. I'm assuming you are connected via the Wi-Fi. The Wi-Fi(data side) is working which uses UDP only and not TCP. The audio side uses UDP and TCP. I would investigate why the TCP is being blocked. I would start by power cycling the computer, scanner, and router. Next double and triple check that another program running is not blocking the TCP to the scanner.