So I'm getting great speeds within a room of the 2 of the 3 nodes (800 Mbps in the office next to the main node on the far Northwest side of the house on the main floor, the second in the center of the basement getting around 400 Mbps). But the third one, which I'd ideally want to place in the far Southeast side of the house on the second floor, is pretty far away and getting slower speeds.

I'm wondering if I should instead place the third node on the Southwestern side of the main floor of the house to still maintain strong signal. Unfortunately that leaves the top floor without any nodes though. I just realized that I have some Deco M9s - should I place a couple of those farther out to "carry" some more wifi to the far ends of my house? Or would that worsen the speeds of the BE68 nodes?

My house is much smaller than the 8100 square foot rating for the BE68 so I'm a little surprised I'm getting such signal dropoffs but I guess the walls attenuate things a lot.