We have multiple servers for a Online Travel Agency websites. Production traffic land to servers in round robin fashion controlled by NetScaler. We have same code for Desktop and mobile site. Only difference is the user interface look and feel (UI). Conversion ratio of look to book is very good on Desktop users but much lower in mobile device users. Secondly one server does good in terms of Conversion ratio while other does not and difference is huge.
I have verified servers in terms of load and free resources (CPU, RAM etc). All servers look exactly same. IIS also looks same. People look criteria varies 5 to 10 percent but it cannot impact performance where one server's Conversion ratio of look to book is double of other.
We have also used APM tool to check for issues on software and hardware side. If code has issues it should have on all servers because code is same.
I am looking for suggestions on what to check.
Thanks, Pankaj