You want a ceiling-mounted mesh access point to kill dead zones and give every room a fast, wired-like connection. If you buy the right enterprise-grade or prosumer gear, you will install it once and ignore it for the next five to seven years.
Timing matters just as much as the hardware. Wait until new models launch so the previous generation drops in price, giving you top-tier speed for a fraction of the cost.
Remember that the 0% intro APR for 15 months on purchases and balance transfers is a hard deadline, not free money. If you still have a balance left when those 15 months run out, the regular interest rate kicks in on the whole original amount.