Move home or work around the signal limitations.

What is your budget? I got a QNAP with 2 x 8TB drives for just over UKP400

If your house has lots of metal in the walls, you could be living in a virtual Faraday cage.

You’re worrying over nothing. The difference between 20 and 30db is the difference between leaves rustling and someone whispering.

I go for nas-focussed HDDs - Ironwolves and so on. I’d only deploy SSDs if I was running virtual machines with lots of concurrent users.

A former customer of ours had directional antennae. They were flaky and tended to get hit by lightning.