Nginx s2member plugin fix

I use a plugin called s2member which sets restriction levels on pages and posts. When I activate a restriction on a user sign up page, the page is supposed to redirect user to a restricted page upon successful signup. This works fine on Apache but on Nginx the redirect doesn't work, the form gets submitted successfully but due to the s2member restriction and something to do with Nginx the redirect results in a gateway timeout. Need someone to help fix this.