Thick reinforced concrete walls might be one of the best EMF hacks for protection from outside towers

203 mm (8 inches) thick plain concrete wall produced

~29 dB at 2.4 GHz → 99.9% signal reduction
~48 dB at 5 GHz → 99.99% signal reduction

When doubled (thicker), the attenuation roughly doubled (i.e. ~30 dB → ~60 dB) for the same frequencies.

If your WiFi struggles indoors,

It’s not bad signal, it’s actually good shielding.

nnEMF Hack #173