Adding a second nav tier is a discussion worthy of another thread, although the implementation could be somewhat involved. It would still be nice to have the thought exercise of what a potential 2-tier nav could like like (without confusing existing users).
edit: Another option is to see if there are any pages that can logically be combined into a new page that page has them as tabs instead. For example, moving Status > DHCPv6 Leases into Status > DHCP Leases and creating v4 and v6 tabs (I have not idea how hard or what implications that might have)