Apropos of nothing, a conductive mesh with 1/2" holes suffices to block 2.4 Ghz signals, while 1/4" holes suffice to block 5 Ghz signals. https://www.homedepot.com/s/hardware%20cloth
Hah, I remember having a tiny condo and was unable to get wifi throughout it because it was constructed with a metal-mesh backing[1] instead of wooden lath for the plaster. Was like a 60db drop putting a device on the opposite side of a wall made from one of these.
1: Kind of like this https://www.homedepot.com/p/Gibraltar-Building-Products-3-4-...