jcjenkins,
re: X-Payments callback IP
Yes, that's X-Payments server IP address and I corrected X-Payments user manual to be more clear on that. Also, we adding a tooltip/hint near that setting in X-Payments configuration in future X-Cart v4.x version that we are going to release after 4.5.5.
Re:
> Reason: Gateway reported of successful transaction but it's response came from
> the IP that is not specified in the list of valid IPs: XX.XXX.XXX.163 (I Xd out the
> numbers). The IP it's showing is the IP of the computer from which I placed the
> order.
It looks to be an issue with your payment gateway account setup rather than with X-Payments. Namely, your gateway locks some IPs where transactions are coming from.
Also, check
http://help.x-cart.com/index.php?title=X-Cart:User_Access_Control