Well you never said $50 and/or second hand, so I assumed you meant new.

When you buy an Optiplex you send money to Microsoft (at least on the US website, regardless of configuration it seems). I stopped doing that kind of thing years ago. I would be fine running Linux or DD-WRT on it, though.

Is there no extension card on the market providing this?

Fair enough. In my setup, what needs to be wired is wired. The rest is not sensitive when it comes to speed.

Thanks for the tip. Has a Windows license though, so hard pass for me. I'll keep exploring.

Something like a Pi 5 or faster, with dual NIC (>= 1 Gbps). With the intent to run Linux.

I forgot to mention, the learning experience is interesting. And I don't even work in IT. But I was a somewhat early internet user and have an interest in tinkering.

Happy to answer. My router / WifiAP is currently a device controlled by my ISP. This means a few things:

• My ISP can (and has) rebooted my router remotely. My ISP can run any code they want on a this router which is on my local network. I don't like that. I don't trust them. They have a history of selling customer data. I would like to eliminate the possibility of any nefarious action from them.
• The router has an admin interface that is somewhat limited. I do not have access to certain functionalities that would be say on a Linux machine. And again, I've been doing that since the days of ipchains. An example that comes to mind is drop all packets coming from a terrorist country making hundreds of thousands of attempts a day on my SSH daemon. Or have control over what nameserver and domain information is sent by the DHCP (I hate the wildcard domain resolution of my ISP). Or block packets to/from known advertisers to a blackhole. Things of that nature

Essentially, I want to defend myself against malicious individuals and corporations and nation states.

I hear you.

I agree. If I was younger with more time to spare I'd do it though.

It can also be a task that is more or less involved. I've been using Debian for almost 25 years now and have enough accumulated knowledge that some things are easily and rapidly done. I recently stumbled on some IPv6 prefix delegation issue when trying to run my own router and gave up though, not worth my time. But it's on my list.

To have more control over what happens?

*unintended

I'm not predicting any scenario in particular. I'm just worried about possible unintended consequences when drastic action is taken (and that is true also for geo-engineering). Blocking the sun on a scale large enough to matter seems prone to intended consequences. But maybe that's just me.

Isn't such a drastic move that it might be too late when / "if it causes problems"?

It's not like we need the sun for anything. What could possibly go wrong?