Why does my GS1900 allow multiple devices on one 802.1x port after the first authenticates?

Zyxel_Judy

This is expected behavior on the GS1900 series, because it does not support a configurable host-mode. Once the first client successfully authenticates on the port, any additional devices connected on that same port are allowed access without needing to authenticate themselves.

There are two ways to address this, depending on your setup:

1. If you need strict per-device authentication (e.g., to prevent someone from bypassing 802.1x using a hub or micro switch), you'll need a switch model that supports configurable host-mode — for example, the GS1920 series, using the "Multi-Secure" host-mode setting.
2. If you only want to allow a single client on the 802.1x port (on the GS1900 itself), you can combine 802.1x with Port Security and set the Max MAC Entry Number to 1. This is configured under: Configuration > Security > Port Security > Port.