I tried to study a bit from beej.us and I appreciated the style of teaching, but ultimately thought it wasn’t for me as it didn’t go much into depth and focused more on creating C programs. Is there some source from where I can learn in a comprehensive yet easy to understand manner the fundamentals of computer networking, at least to the extent that is relevant for selfhosting?


Honestly, Cisco still is king for this. Look for some CCNA training courses to get a proper education on networking. Just get the material, don’t worry about the exam.
YouTube, CBT Nuggets, and INE all have plenty of courses.
Yup. And the official training books are still a great resource for learning everything from the basics to more advanced stuff.
I bought an updated set a couple of years ago, and they still hold up.
I still reference my Cisco Press CCIE routing TCP/IP volume 1 and 2 from 2005