Practical Networking (practicalnetworking.net) is the teaching brand of Ed Harmoush, a network engineer and CCIE who publishes some of the clearest networking-fundamentals content on YouTube and through his paid courses. His material focuses on building the mental model of how networks actually work rather than memorising vendor-specific commands.
The CourseFlix listing carries two Practical Networking courses on networking fundamentals and the protocols underneath the modern internet. Material is paid and aimed at developers and aspiring network engineers who want a real grounding in TCP/IP, routing, and switching.