The Devices supported by OpenWRT with full details page is a great place to start looking for hardware.
Here are some hardware requirements to start with. Minimum configuration would be a good place to start for simple experimentations, but you will quickly start seeing issues when running services like Samba.
|RAM||32 MB||>=128 MB|
|Flash||8 MB||>=16 MB|
|WiFi||2.4 GHz 802.11 b/g||2.4 GHz 802.11 b/g/n, 5.0 GHz WiFi|
|USB ports||1 USB 2.0||>1 USB 2.0 or 3.0|
|Ethernet ports||1 WAN + 4x LAN||Gigabit Ethernet|
|Serial||-||Yes (or JTag)|
|JTag||-||Yes (or Serial)|
JTag, and serial ports come in handy when recovering a bricked device. I have never had to use either after 10+ years of experimenting with routers (knock on wood), but it is good to have just for in case.
Things to keep in mind while searching:
- Use the white fields in the column headers to help narrow down your search. Here is a filtered list containing currently available routers, supported in 15.05, 128 MB of RAM as an example. Experiment with the filters.
- Flash is critical. It dictates how many packages can be installed on a device.
- There is a good chance you cab still be able to get items that are listed as Discontinued. In some cases you might be able to get them at batter prices. Just search around on the web.
- Supported Current Rel should be OpenWrt version 15.05 or higher. This might not be accurate, look at the devices wiki page and the OpenWrt Downloads to get a more accurate account of it is supported.
- Look at the OpenWrt hardware wiki page for the devices. Look for detailed installation instructions, how to recover bricked devices, how well it is documented. This page is very important when it comes to device specific questions that will come up. OpenWRT's WNDR3800 wiki page is an example of a good one.
- Take a look at the OpenWrt forum. Here is the WNDR3800 forum page as an example. Note that the entries are listed oldest to last, which is a bit confusing and gives a false sense of inactivity.
I am using the Netgear WNDR3800. The Netgear WNDR3800 made its debut back in 2011. It might sounds a little dated, but it with 128 GB or RAM, 16 GB flash, two dual band antennas, Gigabit Ethernet ports and then some, it should be more than adequate for the job.
The following summary was pulled from OpenWRT's WNDR3800 wiki page.
|Name||WNDR3800 - N600 Wireless Dual Band Gigabit Router - Premium Edition|
|CPU||Atheros AR7161 rev 2 680MHz|
|Wireless Chipsets||AR9220 + AR9223|
|2.4 GHz WiFi||802.11 b/g/n|
|5.0 GHz WiFi||802.11 a/n|
|Notes on wireless||Simultaneous dual band (2.4 and 5 GHz) with dual-stream N.|
|Ethernet ports||1 WAN + 4x LAN (Gigabit Ethernet)|
|USB 2.0 ports||1|