Add OpenWrt router guide

docs/routers/openwrt.md

@@ -0,0 +1,76 @@
+# OpenWrt
+
+Here's a short guide to configure Pi-hole as the DNS server for your OpenWrt router.
+This guide was written for OpenWrt version 24.10 but the principle should hold for any earlier or later release although Web UI might look different.
+
+## Requirements
+
+* OpenWrt router (already installed and accessible)
+* Pi-hole installed on a device in your network (e.g. Raspberry Pi or LXC container)
+* Access to OpenWrt LuCI Web Interface or SSH terminal
+
+## Configuration
+
+Ensure Pi-hole has a fixed IP. For example: `192.168.1.2`.
+
+### Option 1: Tell DHCP clients to use Pi-hole (Recommended)
+
+#### Web UI: Network > Interfaces > LAN
+
+For the selected interface, eg *lan*, click *Edit*. Then under *DHCP Server* > *Advanced settings* set *DHCP-Options*:
+
+`6,192.168.1.2`
+
+*Meaning: 6 = DNS server, followed by IP.*
+
+![Screenshot of OpenWrt interface DHCP settings](../images/routers/openwrt-dhcp-options.png)
+
+#### Terminal:
+
+```shell
+$ uci add_list dhcp.lan.dhcp_option='6,192.168.1.2'
+<no output>
+$ uci commit dhcp
+<no output>
+$ /etc/init.d/dnsmasq restart
+<no output>
+```
+
+### Option 2: Forward requests to Pi-hole
+
+*Note: This makes all requests look like they come from the router in Pi-hole.*
+
+#### Web UI: Network > DHCP and DNS > Forwards
+
+Add your Pi-hole IP under DNS forwards
+
+![Screenshot of OpenWrt DNS forwarding settings](../images/routers/openwrt-dns-forward.png)
+
+#### Terminal:
+
+```shell
+$ uci add_list dhcp.@dnsmasq[0].server='192.168.1.2'
+<no output>
+$ uci commit dhcp
+<no output>
+$ /etc/init.d/dnsmasq restart
+<no output>
+```
+
+### Restart Network Clients
+
+Reboot your devices or release/renew their DHCP leases so they pick up the new DNS server.
+
+## Verification
+
+On a client, run:
+
+```shell
+$ nslookup example.com
+Server: 192.168.1.2
+Address: 192.168.1.2#53
+```
+
+Ensure the server address is your Pi-hole IP.
+
+Visit the Pi-hole dashboard and check query log for activity.

mkdocs.yml

@@ -217,6 +217,7 @@ nav:
     - 'Fritz!Box (EN)': routers/fritzbox.md
     - 'Fritz!Box (DE)': routers/fritzbox-de.md
     - 'Nokia G-240W-B': routers/nokia-G240WB.md
+    - 'OpenWrt': routers/openwrt.md
     - 'OPNsense': routers/OPNsense.md
     - 'TP-Link': routers/tp-link.md
     - 'Ubiquiti USG': routers/ubiquiti-usg.md