At first I thought I was missing something, but a check with ZyXEL confirmed that there are no controls for the B-4000's firewall. This means no DMZ, no outgoing port/service filters, no virtual servers, no content controls, etc. So if you need anything beyond basic Internet sharing - and the ability to host a controlled-access hotspot, of course - for wired and wireless clients, the B-4000 isn't the product for you.
The other important thing to know is that the B-4000 takes its gatekeeper duties seriously - maybe too seriously for anything except hotspot use. First, the B-4000 treats wired and wireless connections equally, so it's not possible to force authentication only on the wireless side while letting the wired clients freely access the Internet.
What's more, the B-4000 implements a Level 2 V-LAN (virtual LAN) on all traffic, meaning that not only is access blocked between wireless and wired clients, but from wired-to-wired and wireless-to-wireless clients too. To put it simply, each client is on its own private network that connects only to the Internet and nowhere else. This means that each user's privacy is protected, but forget about file and printer sharing!