Zyxel GS1900-16 wired switch basic setup

Installing and Using OpenWrt Network and Wireless Configuration
1

I have a Zyxel GS1900-16 switch which I'm having trouble getting basic functionality working.

I assumed that it would work like an unmanaged switch out of the box, but it does not.

I have an untagged RJ45 cable from another network device. If I plug this cable into my pc I get a dhcp address, but if I plug this cable into the switch and my pc into another port on the switch I don't get a dhcp address for my pc.

Do I have to add dhcp (and other) firewall rules to get the device to act like an unmanaged switch? If so, any guidance or example on what to do?

I have invested many hours trying the following in vain:

  • I have tried adding differing flavors of dhcp firewall rules.

  • Setting up bridge devices, like for a dumb access point, which I have several that work fine.

  • Changing the lan interface vlan id to match that of the upstream network device

  • Changing the lan management interface address to the same subnet as the upstream network device

Any help would be appreciated, thank you.

For reference

The switch system details are:

Screenshot from 2026-01-30 02-35-40
Screenshot from 2026-01-30 02-35-40875×229 7.14 KB

The raw network config (redacted) is:

config interface 'loopback'
    option device 'lo'
    option proto 'static'
    option ipaddr '127.0.0.1'
    option netmask '255.0.0.0'

config globals 'globals'
    option ula_prefix 'xxxx:xxxx:xxxx::/48'

config device 'switch'
    option name 'switch'
    option type 'bridge'
    option macaddr 'xx:xx:xx:xx:xx:xx'

config bridge-vlan 'lan_vlan'
    option device 'switch'
    option vlan '1'
    option ports 'lan1 lan2 lan3 lan4 lan5 lan6 lan7 lan8 lan9 lan10 lan11 lan12 lan13 lan14 lan15 lan16'

config device
    option name 'switch.1'
    option macaddr 'xx:xx:xx:xx:xx:xx'

config interface 'lan'
    option device 'switch.1'
    option proto 'static'
    option ipaddr '192.168.1.1'
    option netmask '255.255.255.0'
    option ip6assign '60'
2

It kind of does, apart from the management interface - and that it cares about VLANs, rather than (maybe- or maybe not) passing them through.

Not relevant for switch usage.

Not useful.

As long as we're only talking about untagged packets, this is not necessary (but may be useful in the long term, if you do want multiple VLANs).

Should be in the same subnet and not overlap with other devices (so presumably NOT 192.168.x.1).

That depends on what you actually want to set up, at least for today.

If you want to start as you would with an unmanaged switch (and NOT relying on any implicit VLAN mishandling some unmanaged switches might allow you to get away with).

  • reset to factory defaults
  • configure a valid IP address out of your main LAN (I'm a fan of DHCP and static DHCP lease reservations, but feel free to use a static address)
  • connect LAN1 (well any port, but let's keep it simple for now) to your normal LAN, use a browser to connect to luci or ssh to get a shell, confirming the management interface is part of your LAN and accessible
  • you're done, LAN1-16 will all carry the same network, untagged

Once you actually do want to use managed switch features, DSA configuration is your go-to guide. Just in general (unless you know why you want it otherwise), only a single interface (the management i/f) should have an IP address, all others are just proto=none. More details needed for specific VLAN configurations.

3

Firstly, thank you very much for taking the time to help me.

I have tried this before, but I followed you advice above step by step without success. I think there is something wrong with my device.

Here’s what I did:

  • Factory reset

  • Changed lan interface protocol to DHCP

  • Connected main lan cable to port 1

  • No dhcp lease was registered on my main router

  • Checked the lan cable was live by plugging it directly into my pc and immediately received a dhcp lease.

  • I also tried with a static lan address, but with similar results.

I had an issue with the initial install of OpenWrt (see here), so maybe I need to re-flash or something. I did upgrade to the latest OpenWrt version, so maybe I’ll try another version.