Transmitting data in a house which strongly attenuates RF signals
Use powerline networking, X10, etc.

User lower frequencies which penetrate walls better than higher frequencies, such as the 433 MHz band rather than 2.4 or 5 GHz.

Drill holes, run wires, put a wireless access point in each room.

Run fiber optics or wire everywhere, connect all your sensors and devices via fiber optics or wires. Also known as (hammer) Drill, baby, drill.

If " LiFi " ever gets past the hype stage it might offer an option (you'd need to pass it through doorways, or course), but at present it looks like lots of hype, no product, though I suppose you could use the concept to roll your own system.

It would be kinda retro-cool to have speaking tubes all over the house connected to 300 baud acoustic couplers, but it might also get a little wearing (background noise-wise) unless you have really good acoustic isolation, and of course if you had the tubes in place, they'd make perfectly good conduits.