Buy a new N100 microPC with 32GB RAM and m.2 drive, Sabrent 5-bay USB_3 DAS, a couple 10TB drives. Easy low-power single box home server with room to expand. You also could add a good switch and box of Cat8 (cable always > WiFi)

Spend the rest on another hobby!

Home Assistant.

Whoa! My IP has never moved around that much.

If you want a little more security, use a firewall to whitelist your other players and block all other connections. It's another thing to maintain, but ISP IPs don't usually change very often.