I have a Zyxel Zywall Prestige 334W Wireless Roter/Firewall. When one machine is connected to any port it fnctions properly. When a second PC is connected the firewall drops both connections. The firmware has been upgraded to the latest release. the device is configuurded to allow 5 connections. What else could be causing this issue? I have another device that works fine so it's not the ISP.