Need to rewrite with LTM

Hello Rafi, if I'm not mistaken you're having the same issue as this post here. 

- globalserver.mydomain.com should resolve to your VS IP 
- if SSL is in place, you need a clientSSL profile with a certificate that matches "globalserver" SNI (or wildcard for *.mydomain.com) 
- you need HTTP profile on the vitual server to parse request elements 
- if backend server speaks SSL, you also need a serverSSL profile

iRule should be pretty simple, this code will rewrite client request before sending it to server -- meaning it will be transparent to client. 

when HTTP_REQUEST {
  if {[string tolower [HTTP::host]] eq "globalserver.mydomain.com" }{
    HTTP::header replace Host "internalserver.com"
    HTTP::uri "/portsluser/main#page/"
  }
}

My only concern would be that you have hash "#" character in URI, which is a reserved character that is usually only interpreted by client browser (usually not passed to server) to identify a fragment.