Callback Error (Authorize.net AIM emulator)

I have been beating my head against the wall on this one. I read just about every post regarding these types of issues and still could not find an answer. Perhaps @Qphoria could help. I see you have a vast knowledge on this subject.

Running 1.5.5.1, I am using the Authorize.net(AIM) with a company called eprocessingnetwork.com who has an authorize.net emulator. 95% of the time this works fine.

About 5-10% of the time I am getting a cURL 28 time out error. The credit card is being charged, but the callback is not completing and the customer either just sees the 'please wait' message, or gets the cURL error 28 message. The order shows up as a missing order, and no email is sent.

I have increased the timeout from 10 to 20 seconds thinking that might help - it did not.
I read it might be a DNS cache issue, but have not traveled down that road yet.
Perhaps a port blocking issue with my webhost? (dedicated server on hostgator) doubtful since it works most of the time?
My only other thoughts are that the script is trying to complete other functions before writing to the screen, which is causing the time out.
It seems it has to be an issue on my server, but can not pin-point the problem.

Does Opencart/authorize.net(AIM) perform other functions before writing to the screen, like email, writing to the database, etc? Maybe this is the problem?

I am really lost here, any insight would be much appreciated.

--Marc

Have the same issue using Quantum gateway via authnet emulation. 95% time it works but a few give a timeout error. More seems to be mobile users. Hosting company and Quantum gateway point the finger at each other but I am inclined to think it is Opencart or host related since it happens on different gateways.

It may not happen for a month but lately it started showing up again. We are using v1.5.6.1 but it was happening on 1.5.4.1.

If you find an answer, please post back.

I think I've found the answer as to the "why"

https://github.com/opencart/opencart/issues/212

look toward the bottom of the list at the explanation that @oasisfleeting made May 8, 2014

Auth.net only records 20 characters of the hash, OC records them all. The explanation & the fix recommended makes sense.

Hope this helps others... I've had to dig myself!

Solution: Create your hash from a password or for example i_love_lucy.

Thanks for that DBK!