Most devices that have drivers for XP to connect are G or draft N. Newer consumer routers require compatibility to be enabled, and after that it depends on encryption. I have a PCI Linksys Wireless G card that works great in XP, but I need to turn on A/B/G compat mode in my Ubiquiti stuff and disable WPA2 for it to connect properly. I also have a PCI-E draft N Asus card that connects without all of that but when WPA2 is on it drops connection periodically. When I disable encryption for that SSID the drops stop. Solid solution is just hardwire an XP box if you need network uptime with it.
I forget what my WI-FI adapter was other than it fits in a PCI slot and it seemed to work just fine with WPA2 which I think is what I use for security. Not sure when I got the card though. Maybe around 2012-2013 perhaps so maybe that is why it worked so well.
I use a cable modem that's a few years old which I had to buy back when DOCSIS 3.0 came out.