using two irules in VS

Add

event disable

function to your 1st iRule, after the redirect statement. This will make sure you won't trigger tcl errors of type "multiple redirect/response invocation" when a customer outside 10.0.0.0/8 network requests your website without the preceding 'www.' during maintenance. Any time this tcl error is triggered, a customer will get a "Connection has been reset" error instead of seeing the maintenance page.

Also, rather than using HTTP::redirect, it's better to use HTTP::respond with a Connection=Close header to ensure customer will tear down the existing TCP connection. If a long-lived session prevails, customer may still get the maintenance page upon page refresh even after you have removed the 1st iRule from the VS.

I'd use the following markup myself: ('event disable' function is mandatory, any other amendments are optional recommendations)

priority 499
when HTTP_REQUEST {
  if { not ([IP::addr [IP::client_addr] equals 10.0.0.0/8]) } {
    HTTP::respond 302 Location "https://www.mysite.com/Portals/0/Documents/Learn/LPCFAQs/mocket.png?ver=2016-06-06-090820-970&timestamp=14655037dr5494" Connection Close
    event disable
  }
}