Since the new EE firmware those hidden pages are no longer user accessible, as discussed here, other than the Factory Reset. ADSL Mode can be got off the normal GUI. There is nothing you can do about it; they were not officially released to you.
But why do you need Remote Access to the router? That is Orange's job.
Or do you mean access from the Net to services on your local network? That is handled by the Firewall, NAT and port forwarding in the usual way.
1999: Freeserve 48K Dial-Up => 2005: Wanadoo 1 Meg BB => 2007: Orange 2 Meg BB => 2008: Orange 8 Meg LLU => 2010: Orange 16 Meg LLU => 2011: Orange 19 Meg WBC