PSPortal connection unstable and I don't understand why?

I have a PS5 Pro in my bedroom and base PS5 in my living room.

My house is quite big, so I have a meshnet set up with 3 mini hubs all connected via wifi to my main router.

My PSPro is connected to one of the hubs via ethernet and gets speeds of 400-600mbps on average.

My base PS5 is connected by ethernet to my router, which is in the same room, which gets speeds of 700-900mbps on average.

When I play on my PSPortal connect to the Pro, it works great upstairs with the odd dip in quality if I move to another room upstairs. However, when I go downstairs, the quality drops to like a 360p or less equivalent unless I switch my portal to my base PS5. This also happens in reverse with the base.

Of course, I can keep switching between my consoles by this is highly irritating and inconvenient. Also, it means I have to double up on games between both consoles for every game I am currently playing.

I don't understand why this is happening, especially when I'm connected to the pro but playing downstairs in the same room as the router.