ESPHome moves received Ethernet data into external memory on compatible boards configured for both Wi-Fi and Ethernet. In J. Nick Koston’s Sendspin test on an Apollo CAST-1, streaming previously exhausted internal memory within a second; the correction left 22.8 KB free.
The change requires external memory and a W5500, DM9051, CH390 or ENC28J60 Ethernet chip. Wi-Fi-only and Ethernet-only configurations keep their existing behavior.