So as far as I can understand , your goal is to understand how networks work. If that is correct, then instead of jumping straight to socket programming get a basic overview of networks through books by Andrew S Tenenbaum or by Jeff Doyle ( TCP/IP). Set up a lab using tools such as eve-ng and look at how routers work. Use wireshark to capture packets and get into the habit of analysing them . This iwll give you a look at protocol headers . You may not get an ASIC level of understanding of packet forwarding but I don't think you really need that since most manufactures do it differently.

I have already been through the book by Forouzan. It was incredible. I'll follow your advice to get a better at analysing packets and protocols

I somewhat agree with him. I would, however, jump right into making something you would find interesting as soon as you have a basic understanding of what makes up a packet, the TCP/UDP protocols, and how sockets work, such as an IRC chat clone, a simple networked game, a reusable self auto-updating library, and so on. I would recommend creating something that you'll actually use or remain interested in to stay motivated.

I find I do most of my learning while trying to research my way around a stumbling blocks, but of course it always helps to read/research things beforehand as well.