You have three excellent options when it comes to open-source router software, I have added an 'out-of-the-box' seller, as it is a real gem and worth sharing.
The OpenWrt Project is a Linux operating system targeting embedded devices. Instead of trying to create a single, static firmware, OpenWrt provides a fully writable filesystem with package management. This frees you from the application selection and configuration provided by the vendor and allows you to customize the device through the use of packages to suit any application.
For developers, OpenWrt is the framework to build an application without having to build a complete firmware around it; for users this means the ability for full customization, to use the device in ways never envisioned.
Secure networks start here.™ With thousands of enterprises using pfSense® software, it is rapidly becoming the world's most trusted open-source network security solution.
libreCMC is a set of fully free embedded Operating Systems for general purpose computers. The project aims to give its users freedom and control over the software that runs on their hardware. Most of the hardware that libreCMC supports includes a wide range of routers and some small single board computers.
When it comes to so-called 'smart tech', it is mostly something I would describe as 'intrusive'. Yet, some tech can be just the opposite – safe, private, and useful. One such thing is a router! Well, I hear you, a router? Smart tech? Now think about it, every device in your house goes over the router, right? So having a router that can do more than just provide a connection to your internet could be considered smart. Such a piece of tech comes from GL.iNet.
Their flagship model is Flint. I use my GL-inet setup with it at the moment with Velica (GL-B2200). It's a mesh router.
GL.iNet has all its setup in open-source. This means it runs an open-source software based on OpenWrt. This is pre-installed with OpenVPN, WireGuard Client and Server, one click set up is possible with Mullvad VPN and manually with every WireGuard or OpenVPN provider.
The speed is almost identical at my home as when I wasn't using a VPN. You can also choose Tor as an option on this router. However, I, personally, would not use a Tor router widely, but by device. This said, it is a very nice option to have.
The router also has an internet kill switch, which means that if your VPN goes down, the Internet stays offline until the router reconnects to the VPN.
You can also choose if all your devices are connected to the VPN or only selected devices. Smart, isn't it? ;)
The router also comes with AdGuard Home pre-installed. This means you can maintain blocklists, block and unblock traffic and set your own preferred DNS.
If you don't choose to use AdGuard Home (but why wouldn't you?) you can set your own DNS in the DNS settings menu. This includes NextDNS pre-installed.
These routers cover everything when it comes to privacy, and you don't need to flash or study anything to get it running.
However, the biggest problem some people face is the coverage in the house. With mesh technology, some routers, including the Velica, have you covered. Not just that, the mesh router nodes have almost the same speed as the main router.
You can see and maintain, block, devices etc. from one single router hub. Additionally, you can switch to a VPN connection on the fly – which is useful if you watch a football match that is blocked in the country you just had as your router VPN ;) (I learned this last weekend when we had real trouble watching R*****s TV.)
File sharing on the device is possible, and the Velica has an 8GB storage built-in.
Firmware updates can be automatic or manual. If you chose automatic, the firmware will be installed on all your nodes and devices.
I am usually not someone who recommends buying products, and this is by no means an article with a referral link, but I've been using GL.iNet for years and can recommend the products because I use them daily without issues.
Check out GL.iNet travel routers, MiFi and mesh routers as it is a game changer for everyone who wants to have privacy at home, yet doesn't have the time or knowledge to flash a router the way GL.iNet does. The addition of AdGuard Home is unique and impressive.