"it is true that the gateway, which was developed in 2001, badly needs replacing."
Why?
Because it has been running for 14 years without a TalkTalk style incident?
Or because some 15 year old script kiddie doesn't yet know how to break it ?
Sorry - just because something has been around for a while is NOT the reason to replace it. (Unless we are talking about that sandwich in my work drawer with a best-by date of 15/03/08..)