I finally got this issue resolved. The issue with this Port 75 is not on our customers' firewall. Yes, there are some servers that are filtering Port 75 outbound. But even after we configured rules for outbound Port 75 to my hosted Automate server only, it still did not work. Finally, I re-opened the ticket to request to restart Ltredirector service on the hosted Automate server, whereas a competent Tier 3 took over my ticket. It turned out that the firewall rules on the hosted Automate itself did not have rule for UDP Port 75.