Where to learn more about fundamentals & trends in network architecture?

I'm hoping some of you can help me out in terms of some learning resources on the following:

• Data center architecture
• Hybrid/multi-cloud networking best practices
• NFV
• SD WAN

For some background, I am moderately well rehearsed on the topics and have been working in sales for a data center company for about 5 years. I am extremely comfortable having these conversations but would like to elevate my knowledge to the next level. Staying up to speed with the trends and emerging technology is incredibly important to me so any of the websites you go-to for news would also be helpful.

I recently picked up the book "Designing an Internet" by David Clark (feedback from those who have read it is welcome) and have looked at what's out there in terms of courses. There are also three CSP certifications that I am in process of getting.

Also open to more fundamental literature as well. Ultimately, the goal here is to have the most well rounded understanding of what my clients value on a day to day basis.

Thanks for helping me out.