[jack1243star]

Are there links I can read up on this? Ethernet as on-chip bus blows my mind.

I guess it's cheaper than having to redesign an entire SoC, but still...

[doubled112]

These SoCs are often purpose built for networking. The CPU just connects to an internal switch chip instead of an external jack.

Mikrotik makes block diagrams of some of their Routerboards available. This is a hAP AC3, for example

https://i.mt.lv/cdn/product_files/RBD53iG-5HacD2HnD_201031.p...

It runs on a Qualcom IPQ4019 single-chip Wi-Fi system-on-chip (SoC)