They have a series of routers designed to support OpenWRT (which IMO is better then DD-WRT but preferences of course). If it supports OpenWRT then others shouldn't be difficult to load on it either.
Also, it ships with their proprietary "Smart Wi-Fi", not OpenWRT.
> While the Linksys WRT1200AC provides an outstanding experience via Smart Wi-Fi immediately out of the box, advanced users can further modify the router with open source firmware. Developed for use with OpenWRT, an open source Linux-based... [0]
No one, to my knowledge, makes the appropriate Gigabit Ethernet (ideally Dual Gigabit Ethernet) + Wifi Open-Source Hardware SBC that could be used as a router. There are a lot of SBCs with open-source software and mostly-accurate PDFs of their schematics, but very few (the Olimex OLinuXino project, maybe?) that are actually open hardware.
I do understand that truly open-source hardware is a tough sell, as Jay pointed out in his amazing piece "So you want to build an Embedded Linux system" [1]
> People forget that these EVKs are built at substantially higher volumes than prototype hardware is; I often have to explain to inexperienced project managers why it’s going to cost nearly $4000 [2] to manufacture 5 prototypes of something you can buy for $56 [3] each.
And an EVK is likely built at a lower volume than a consumer SBC. The idea that someone can download your hardware design, modify it, and respin it for their desired open-source router but now with a piezo buzzer added might work for Arduino-scale hardware projects but simply isn't reasonable for something that reaches the performance required of a router.
I apologize I misread OP's question. I incorrectly interpreted it as "hardware that supports opensource firmware such as DD-WRT/Tomato".
In terms of hardware like you mentioned there's few open source SBC's at all. Even fairly open hardware like the raspberry pi have a proprietary firmware blob. I guess it will come down to how strictly you define "open source". If you define it as "we have firmware/schematics for every chip on the board" then we'll likely never have that (I don't think even Linksys has that type of access).
I tried OpenWRT a few years ago on my WRT3200acm and the wireless quality was severely lacking. Has a lot changed since then? Do you think it's worth giving another go?
It hasn't been updated since Jan of 2020 but I also don't see any vulns listed for it.
IIRC, the WRT3200ACM had other large issues in regards to wifi... (WPA3 was off the cards because the firmware blob just does not support protected management frames, for example.)
I haven't stayed up to date with them to be honest. I've switched to ubiquiti access points with my WRT1200AC as just a switch/router. My plan is to upgrade to a x86 box with openwrt or something similar.
So if you had issues with the WRT3200acm I'd go a different route
I just tried the wrt3200acm with openwrt for about a month and it wasn’t nearly stable enough. The wifi issue is pretty well know and people seem to be working on it but I’d stay away.
dd-wrt has worked fine for me on this, but I'm a pretty casual user. Couple of video streams and phones, pi-hole, a couple laptops, all of which are idle most of the time.
Also very happy with openwrt on this device. Really quite a decent gui tui and config. Setting up always on open vpn and wireguard was reasonably painless and works well.
They have a series of routers designed to support OpenWRT (which IMO is better then DD-WRT but preferences of course). If it supports OpenWRT then others shouldn't be difficult to load on it either.
https://openwrt.org/toh/linksys/wrt_ac_series
I've had a decent experience with OpenWRT on a WRT1200AC
EDIT: I haven't used it for actual wifi (just routing/switching) in a few years so I don't know how good they are nowadays.
EDIT 2: OP asked for open source hardware, not hardware that runs open source firmware - my bad!