You need to upgrade your firewall to at least 70103.
If there is nothing in the audit I'm afraid we cannot tell you what the problem might be. If some browsers work and some don't I would instantly say "This is not the firewall's fault." The firewall does not care about the browser.
This sounds like a timeout issue outside of the firewall. Not a Connect timeout (a timeout waiting for the SYN, SYN/ACK, ACK to finish), it sounds like a Session timeout. The FW did a 3-way handshake but received no data back after that (which is what that Chrome error basically said).
You should call support to do troubleshooting. You need to upgrade your firewall first though as 70002 is no longer supported.
i hear what you are saying
but why don't we experience this from anywhere else when we try to execute the same process. And also why does it always work with the very first attempt?