Issue #647: Add Radxa Dual 2.5G Router HAT.

_hats/radxa-dual-2.5g-router.md

@@ -0,0 +1,24 @@
+---
+layout: hat
+title: "Radxa Dual 2.5G Router HAT"
+short_description: A Pi 5 HAT for 2 2.5G network interfaces, NVMe SSD, and an additional PCIe device.
+status: prototype
+picture: "/images/hat-radxa-dual-2.5g-router.jpg"
+github_issue: "https://github.com/geerlingguy/raspberry-pi-pcie-devices/issues/647"
+link: "https://docs.radxa.com/en/accessories/dual-2.5-router-hat"
+videos: []
+---
+This HAT includes two 2.5 Gbps Ethernet ports (Realtek 8125BG), an M.2 M-key NVMe slot (2230, 2242, 2260, 2280), and a 12V power input.
+
+The interfaces are adapted through an ASM2806 PCIe Gen 3 switch, with 2 uplinks (the Pi 5 can only use 1), and 4 downlinks—the 4th is exposed as a Pi 5 style PCIe FPC header, so you can daisy-chain other PCIe boards on top of this one!
+
+It has a 40 pin GPIO plug, which supplies power to the Pi, and it is not pass-through type, so you would not be able to mount another HAT on top of this board.
+
+To use the board at Gen 3.0 speeds, after connecting it to the Pi, you need to add the following lines to `/boot/firmware/config.txt`:
+
+```
+dtparam=pciex1
+dtparam=pciex1_gen=3
+```
+
+I am currently testing the board and will update this page with more information later.