ZyXEL GS1900-24HP

The GS1900-24HP is a 24-port Gigabit L2 switch with 170W of PoE power budget.

Support forum: Zyxel GS1900-24HP v1 upgrade from old partition and pinout — no single dedicated “firmware” thread exists for this model; also see the original device-support thread on the lede-commits mailing list.

None at this time.

→ Install OpenWrt (generic explanation)

- → Setting up a TFTP server - → Serial - → Install OpenWrt

* Configure your client with a static 192.168.1.x IP (e.g. 192.168.1.10). * Set up a TFTP server on your client and make it serve the initramfs image. * Connect serial, power up the switch, interrupt U-boot by hitting the space bar, and enable the network. * Since the GS1900-24HP is a dual-partition device, we want to make sure we are manipulating the first partition. Issue the following commands:

setsys bootpartition 0
savesys

* Download the image onto the device and boot from it:

tftpboot 0x81f00000 192.168.1.10:openwrt-realtek-rtl838x-zyxel_gs1900-24hp-v1-initramfs-kernel.bin
bootm

* Once OpenWrt has booted, scp the sysupgrade image to /tmp and flash it:

sysupgrade /tmp/openwrt-realtek-rtl838x-zyxel_gs1900-24hp-v1-squashfs-sysupgrade.bin

→ generic.sysupgrade

* Login as root via SSH, then enter the following commands:

cd /tmp
wget http://downloads.openwrt.org/releases/25.12.4/targets/realtek/rtl838x/openwrt-25.12.4-realtek-rtl838x-zyxel_gs1900-24hp-v1-squashfs-sysupgrade.bin
sysupgrade /tmp/openwrt-25.12.4-realtek-rtl838x-zyxel_gs1900-24hp-v1-squashfs-sysupgrade.bin

→ generic.debrick

→ failsafe_and_factory_reset

Since the partition layout change in 24.10, the stock firmware's backup partition is not usable once OpenWRT has been installed. To revert to the factory image:

* Use the TFTP method to boot the OEM stock firmware image.

* Using the stock firmware's upgrade tools, flash the stock image to both partitions.

For OpenWRT versions < 24.10, you can revert to the backup partition if it is intact.

* To boot the Zyxel firmware from the secondary/backup ROM again, connect serial, power up the switch, interrupt U-boot, and issue:

setsys bootpartition 1
savesys

* Reboot the device. * To return to OpenWrt, repeat with bootpartition 0.

→ Basic configuration After flashing, proceed with this.

→ hardware.button on howto use and configure the hardware button(s).

PoE+ is enabled on all ports when the device is powered on due to the bootloader initiating the PoE microcontroller unit (MCU). This also ensures that the PoE status LEDs on the front of the device work. The MCU's state is not preserved when the device is restarted. Thus, all connected PoE devices will briefly lose power when the switch reboots.

The realtek-poe package is included in OpenWrt images for this device. The included daemon (enabled by default) configures and monitors the MCU, allowing OpenWrt to manage PoE capabilities.

PoE port IDs are different to network interface numbers. The PoE port IDs for this device match. So interface lan1 has PoE port ID 1, lan2 has PoE port ID 2, etc.

The GS1900-24HP v1 uses a ST Micro ST32F100 microcontroller (firmware v17.1) communicating over UART at 9600 baud, and the Broadcom PoE dialect (6x BCM59111 PSE controllers), not the Realtek dialect used on some other models. Setting force_dialect 'realtek' on this device produces garbage values (firmware: v255.255, consumption: 6553.5) and must not be used.

Based on information from /etc/board.json, consider the following configuration in /etc/config/poe:

config global
option budget '170'
option force_baudrate '9600'

config port
option id '1'
option name 'lan1'
option enable '1'
option priority '2'
option power_limit '30000'

config port
option id '2'
option name 'lan2'
option enable '1'
option priority '2'
option power_limit '30000'
(...)

Repeat this configuration for the other ports (up to lan24) to let them be managed by the PoE daemon. Note that name is just a label for the PoE daemon to refer to a PoE-capable port. Making the name the same as the network interface of the relevant port makes management considerably easier.

Without force_baudrate '9600', the MCU replies with garbage data and the daemon log fills with request-bad-checksum errors:

daemon.notice realtek-poe: MCU rejected command: request-bad-checksum
daemon.notice realtek-poe:     CMD:    1c 08 00 00 01 00 02 00 03 00 ff 29
daemon.notice realtek-poe:     reply:  fe ff ff ff ff ff ff ff ff ff ff f4

Make sure to reload the PoE daemon's configuration after making changes to the configuration. Applying changes to the total available power budget requires a restart of the daemon.

PoE command cheat sheet:

/etc/init.d/poe restart

ubus -v list poe

ubus call poe reload

ubus call poe info

ubus call poe manage '{ "port" : "lan1", "enable" : false }'

ubus call poe manage '{ "port" : "lan1", "enable" : true }'

uci set poe.@global[0].force_baudrate='9600'
uci set poe.@port[5].enable='0'
uci commit poe
/etc/init.d/poe restart

To avoid the force_baudrate disappearing issue, use this wrapper script instead of calling UCI directly. Copy it to the switch once and call it from automation tools (e.g. Home Assistant SSH integration):

#!/bin/sh
# /usr/bin/poe_toggle.sh
# Usage: sh /usr/bin/poe_toggle.sh <port_index 0-23> <0|1>
# Example: sh /usr/bin/poe_toggle.sh 13 0   (disable lan14)
#          sh /usr/bin/poe_toggle.sh 13 1   (enable lan14)

PORT_INDEX="$1"
ENABLE="$2"

if [ -z "$PORT_INDEX" ] || [ -z "$ENABLE" ]; then
    echo "Usage: $0 <port_index 0-23> <0|1>"
    exit 1
fi

uci set poe.@global[0].force_baudrate='9600'
uci set poe.@port[$PORT_INDEX].enable="$ENABLE"
uci commit poe
/etc/init.d/poe restart

Port index is port number minus one (lan14 = index 13, lan6 = index 5, etc.).

Front:
Insert photo of front of the casing

Back:
Insert photo of back of the casing

→ Warranty

→ port.serial general information about the serial port, serial port cable, etc.

→ bootloader

None so far.

This page reflects field experience running both OpenWrt 24.10.7 and 25.12.4 on the GS1900-24HP v1, including a confirmed PoE regression and working configuration. See also the related upstream bug reports: issue #18528 (PoE manage command not working on GS1900-24HP v1 with 24.10.x — resolved by reflashing without config retention) and issue #23557 (the 25.12.x PoE regression described above).

luci-port-labels — adds clickable per-port labels to the LuCI Status → Overview page. Developed and tested on the GS1900-24HP (v1/A1 and B1) and GS1900-10HP, running OpenWrt 24.10.x and 25.12.x. Note that 29_ports.js must be patched in place on the target switch — do not copy a patched file from another device as the file differs between LuCI versions.

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