Stop redirecting from mydomain.com/index.php back to mydomain.com possible ?

Hi all,

If I type the url https://www.mydomain.com/index.php, it keeps redirecting me back to https://www.mydomain.com

My problem is that I have a separate welcome and logon page outside of WordPress which is the default page to be loaded when the domain is accessed – default.asp. Once the logon page is completed, the browser should then display index.php but it always then displays https://www.mydomain.com which basically throws me back to the logon page default.asp once again, since that is the default index page for that domain.

Basically, how can I ensure that if I go to https://www.mydomain.com/index.php, that I will stay on https://www.mydomain.com/index.php and not redirect to https://www.mydomain.com

Thanks in advance