I need help bringing ethernet to my server

I'm trying to set up my server a dell power edge 420. My server is loud and proud of its power usage. Anyways my bedroom is upstairs and no good way to bring ethernet up. I don't feel like spending money on a WiFi card because I don't have money for it, but I do have a pi 4 and I was thinking to run the standard os, but use the Ethernet port to share to other comeputers. But my solution is super janky and I want something better.