Begin with two computers.
Learn how to get them to talk to each other via Cat5 line (do not use wireless). These are baby steps.
You do not need any clients. Current operating systems have on board networking capabilities.
Learn how to use routers as switches. Learn how to use modems as keys. Learn how to replace stock firmware on routers. All routers can do similar things. Firmware kneecaps are intentional.
You must learn how to air gap. Air gapping is not optional. Most devices are compromised. Do not use external drives if they have ever been used on devices connected to any network whatsoever.
You will begin to understand why (they) utilize old tech. Discs and Floppy are old, but they are the GOLD STANDARD in reliability for data security.
Learn how to get public radio on your phone (no app or site). Phone hardware contains a full spectrum AM/FM radio antennae. It also can be used as an emitter.
Learn how to faraday your mobile devices with internal modems. ISP not required for mobile phone surveillance. AM/FM is always ‘open’.
Digitize and store all pertinent information on air gapped devices. Replicate data using old tech. Learn how to intake data. Learn how to utilize burner pc’s.
Don’t underestimate “old” tech in times of need. Nellie Ohr used HAM. I suggest learning about radio communications as well.