The problem is that our relay script isn't being requested from Authorize.net according to our web server logs (Apache.) This it not a timeout issue, our script isn't even being requested for some transactions according to our logs.
And our users get this stock message for a timeout error (which isn't even the problem):
"The reporting of this transaction to the Merchant has timed out. An e-mail has been sent to the merchant informing them of the error. The following is the result of the attempt to charge your credit card.
The following is the result of the attempt to charge your credit card.
This transaction has been approved.
It is advisable for you to contact the merchant to verify that you will receive the product or service.
The server uses TLS 1.2: https://www.ssllabs.com/ssltest/analyze.html?d=ubfoundation.buffalo.edu&latest
As with other reports, this began about 3 weeks ago, it's intermittent, around 5% of transactions encounter this problem.
I was pointed to this forum for assistance as the official response from Authorize.net's support center which isn't exactly promising.
Is it possible that someone at Authorize.net can investigate if they are even getting a response from our server when Authorize.net sends a request to our relay URL? I can provode transaction ID's and any other info needed to help investigate.
Bump. We've disabled support for both TLS 1.0 and 1.1 leaving TLS 1.2 as the only supported and enabled version. Still the issue is happening. No entry in Apache logs. No entry in the iptables log for any request at all for our relay script.