Foil shielding will be best, and tighter metallic fabric weaves.
5G is not "5 Gigahertz". It is mostly in the 20 to 60 Gigahertz range, meaning very small, sub-millimeter wavelengths that can creep in through shield crevices.
http://www.createhealthyhomes.com/five_g.php
Jim West
New York, NY
harvoa.org