Since the article assumes the presence of a WiFi network, you can just use a WiFi to Ethernet bridge, about $40

But how do you authenticate to the wifi if the old PC doesn't have WPA capabilities?

	▲	bdcravens an hour ago \| parent \| next [-]
		The PC doesn't. The device does, and the PC is oblivious to where the signal coming along the ethernet wire came from. The issue you're describing would only be relevant is we used a USB (or other connection type) Wifi adapter.
	▲	ssl-3 5 hours ago \| parent \| prev \| next [-]
		That's a problem for the bridge device to sort out, not the hardwired ethernet gear that it connects. Pre-made wireless bridges generally have web interfaces (and/or dreadful phone apps) to get them set up and chatting the right way. It's a process that's very similar to that of configuring a home network router, except the bridge works in the opposite direction. In this way, the devices with ethernet jacks have no idea what things like WEP, WPA, or wifi even are. And that's kind of the whole point. :)
	▲	jasonjayr 3 hours ago \| parent \| prev [-]
		https://docs.gl-inet.com/router/en/4/user_guide/gl-mt300n-v2... These devices have the wifi/ethernet bridge functionality being discussed, (as well as a bunch of other stuff) and are OpenWRT based. Built in openvpn/wireguard as well. We bought a bunch for our team way back when (IIRC they were < $20 USD then) Gl.iNet has other similar more powerful devices as your use case may need.