> Do tell because as far as I'm aware Maxwell's equations don't have an asterisk on them that say "doesn't work below 1 GHz".
Did you really just pull out Maxwell's equations?
EM interacts with matter in different ways. Glass hardly attenuates visible light, but wood does. 2.4 Ghz can pass through walls better than 5Ghz.
There's the concept of permittivity wherein Maxwell's equations are defined in free space with vacuum permittivity.
https://en.wikipedia.org/wiki/Vacuum_permittivity#Permittivi...
To accurately model EM waves, you need more than just Maxwell's equations. You require material equations to model interactions of EM with media.
If you want to get really advanced, whereas Maxwell's equations are classical physics, there's Quantum electrodynamics (QED) which can model interactions of EM and matter.
https://en.wikipedia.org/wiki/Quantum_electrodynamics