@lostless Yep, the wireless router, PS5, pi, Nintendo Switch and smart TV are all within a couple meters of each other in the living room. Like I said, I didn't experience any issues using the pi upstairs. Thanks for your help here, I never would have considered that to be the issue.
I might just have to go wired when using the pi in the living room as I don't have an option to move the wireless router.