Maintenance Redirect and Return

It will be difficult to analysis iRule without seeing it. I am using below iRule since long time.

You can control Pool member from server level and route the traffic.

Example:

when HTTP_REQUEST {
    if { [active_members POOL-NAME] < 1 } {
            HTTP::respond 200 content [ifile get maintanence_page.html] "Content-Type" "text/html"
         }
     }

Thanks