That's because neither AM4 nor AM5 include provisions for a NIC (MAC) on the SoC. Afaik the chipsets don't, either. Intel chipsets generally have a gigabit MAC,

That's because neither AM4 nor AM5 include provisions for a NIC (MAC) on the SoC. Afaik the chipsets don't, either. Intel chipsets generally have a gigabit MAC, but this is rarely used (apparently it specifically requires an Intel PHY and that's more expensive than a complete NIC from say Realtek). Only the Embedded chips have MACs built in.