OPN/pfSense have been mentioned.

Don't waste time with WiFi on the gateway itself as most WiFI chips you can buy are crippled in firmware for regulatory reasons. Just use a dedicated commercial AP hooked up directly or VLANed.

Once you get comfortable with something like pfSense I highly recommend switching to regular Free/OpenBSD, or Linux depending on what you're comfortable with. I find it much easier to manage a gateway with the entire configuration in version control than a GUI. There aren't that many services that a gateway needs to run.

If you feel like you'll miss pf on the *BSDs check out nftables on Linux. It's not as well documented but it's much less painful than iptables.

To loop this into the UPnP discussion: when you build your own gateway from scratch you have to add a UPnP daemon and configure it yourself, instead of forgetting to disable it and exposing poorly configured IOT stuff.

I like Mikrotik for routers. They're cheap and have a lot of knobs in the SW (maybe too many if you just want NAT). They do run linux, but their SW isn't open. I've been pairing my Mikrotik hEX with a Unifi AP. Not sure what I'll do going forward, as I've heard Mikrotik's APs aren't as good as their routing and switching hardware.

If I was going the "dedicated machine" route, I'd probably go with OPNsense nowadays.

The PC Engines hardware line is popular here. The firmware is coreboot and you can run OPNsense on it for an entirely free software solution. It's quite solid, have had no issues at all. See e.g. https://www.pcengines.ch/apu4d4.htm

Not aff'd, just a customer.

Hardware wise, I run Ubiquiti EdgeMAX but I wouldn't recommend them anymore, their software has gone down hill since many of their best developers left.

Software wise, pfSense is where it's at, but I don't have experience with their own hardware other than the ones we ran at work all failed due to a silicon flaw in the Intel SoCs they ran.

Look at the range of devices from GL.inet. They run a custom version of openwrt with a nice UI on top. But most are upstreamed and you can flash vanilla openwrt on them. They re quite cheap as well. I m not affiliated with them but I have bought devices from them. I use one between the router s ISP and my home network.

OPNsense or pfSense

Not pfsense.

https://github.com/doktornotor/pfsense-still-closedsource