you the maximum data throughput (See Claude Shannon). Bandwidth is the amount of spectrum available to transmit in. For instance, a wifi channel in the 2.4 GHz spectrum is 20 MHz wide (with exceptions in newer revisions which add channels together to increase throughput). You also hear about cellphone carriers buying spectrum, same concept. Rain, snow, and distance increase the amount of fade, which requires more transmit power to compensate or else data throughput goes down.

Math, Math, Math, even going to space, LEO or GEO, you can get more than 1 Mbps out of it because you're using pretty wide channels which are available because you are dealing with data above (for anything meant for typical consumers where some amount of weather and non-reliability is okay if it means more throughput) 40+ GHz. That means you have to have some pretty sophisticated timing available, but it's been economical to have that for consumers for over a decade now. This gets into the same thing you more commonly hear when talking about mmWave in 5G, i.e. the actually really fast part of 5G.

[Post edited by jmanatVT at 03/22/2021 4:06PM]