[PROJECT INTRODUCTION & SYSTEM ARCHITECTURE]

This project implements a compact embedded router architecture based on
ESP32-S3 + Dual W5500 Ethernet controllers + 4G Cat.1 modem + Wi-Fi AP.

It reproduces the structure of commercial SOHO routers, but at MCU level, providing:

• WAN/LAN separation
• Auto role-switching Ethernet (W5500 Card0)
• Dedicated LAN port (W5500 Card1)
• Wi-Fi AP in independent subnet (192.168.5.x)
• Dual Ethernet subnet (192.168.4.x)
• 4G modem as backup WAN (PPP)
• DHCP, NAT, bridge, and routing on ESP32-S3

Key Components

• ESP32-S3 — NAT, bridge, PPP, DHCP, AP
• W5500 × 2 — Dual-port Ethernet over shared SPI bus
• EC600N / A7680C 4G Modem — USB PPP fallback WAN
• Wi-Fi AP — 192.168.5.x subnet

Port Roles

• W5500 Card0 — Dynamic WAN/LAN switching
• W5500 Card1 — Always LAN + DHCP server
• 4G LTE (PPP) — Backup WAN fallback

[DATA FLOW DIAGRAM]

LAN1(W5500-1) ──┐
           │
LAN2(W5500-2) ──┤── ESP32-S3 (NAT/Bridge/AP/PPP) ── WiFi AP
4G PPP Modem (EC600N)   ─┘

[ENGINEERING SIGNIFICANCE & INDUSTRIAL VALUE]

1) Industrial router structure replicated on MCU

ESP32-S3 successfully implements:

• Dual Ethernet
• Wi-Fi AP
• 4G WAN failover
• NAT, DHCP, DNS, routing

This positions the architecture between:
Single-port W5500 devices ↔ Full OpenWRT Linux routers

2) Dual W5500 implementation is technically rare

• Shared SPI bus
• Independent CS/INT/RESET
• PHY addressing
• Auto WAN/LAN switching

This project becomes a valuable reference for dual-port embedded Ethernet design.

3) Ideal for low-power field gateways

Applicable to:

• Energy systems
• Factory devices
• Remote monitoring nodes
• Industrial telemetry
• Edge IoT with LTE redundancy

[ARCHITECTURE COMPARISON — TABLE]

[MARKET & STRATEGIC IMPLICATIONS]

1) Filling the “MCU router” market gap

A new tier emerges:

SPI NIC → MCU Router → Linux Router

2) Strengthens W5500 ecosystem

Demonstrates that W5500 can be used not only for single NIC but also:

• Dual-port router
• Field gateway
• LTE backup edge node

3) Synergy with WizFi630S

Not a competitor.
It’s a lower-tier hardware router suited for:

• industrial micro-gateways
• battery systems
• ultra-low power deployments
  while WizFi630S covers:
• mid-tier & consumer routing workloads

Together they form a portfolio, not a conflict.

[AUTHOR SUMMARY — Condensed]

lyxer123 is an applied embedded network engineer skilled in ESP-IDF, W5500, multi-interface routing, and USB-PPP modem integration.
He successfully reproduced a commercial router-grade architecture at MCU level, including dual Ethernet, Wi-Fi AP, 4G failover, and NAT/bridge logic.
His work provides a rare, high-quality reference that expands practical W5500 usage in real embedded gateway designs.

[PROJECT INTRODUCTION & SYSTEM ARCHITECTURE]

이 프로젝트는
ESP32-S3 + W5500 두 개 + 4G Cat.1 모뎀 + Wi-Fi AP로 구성된
초저가·초저전력 임베디드 라우터 구조다.

상용 SOHO 라우터의 구조를 MCU 수준에서 그대로 재현했으며,

• WAN / LAN 분리
• W5500 Card0 자동 WAN/LAN 전환
• Card1 고정 LAN + DHCP
• Wi-Fi AP 독립 서브넷(192.168.5.x)
• W5500 듀얼 서브넷(192.168.4.x)
• 4G PPP 백업 WAN

까지 완전한 형태로 구현됐다.

[전체 데이터 흐름도]

LAN1(W5500-1) ──┐
           │
LAN2(W5500-2) ──┤── ESP32-S3 (NAT/브리지/AP/PPP) ── WiFi AP
4G 모뎀(EC600N)   ─┘

[ENGINEERING SIGNIFICANCE & INDUSTRIAL VALUE]

1) 산업용 라우터 구조를 MCU로 축소 구현

보통 Linux SoC(OpenWRT)에서 처리하는 기능을
ESP32-S3가 단독으로 수행.

2) 듀얼 W5500 완성형 레퍼런스로서 가치

• 공유 SPI 버스
• CS/INT/RESET 독립
• PHY Address 구분
• 자동 WAN/LAN 전환

이 조합은 실제 산업 설비에서도 유효한 고급 구조.

3) IoT 현장 게이트웨이에 최적화

• 전력 소모 최소
• 저비용 BOM
• 4G 백업 필수 장비에서 강점
• 임베디드 장비 내부 라우터로 적합

[비교 테이블 — MCU Router vs WizFi630S vs OpenWRT]

[시장·전략적 시사점]

• W5500 생태계 확장: “Dual Ethernet Router” 레퍼런스
• WizFi630S와 충돌이 아니라 포트폴리오 상호보완
• 초소형 산업 게이트웨이 분야에 현실적 수요 존재
• 초저전력·초저비용 라우터 시장층을 새로 창출

[AUTHOR SUMMARY]

lyxer123는 ESP-IDF, W5500, 멀티인터페이스 라우팅, USB-PPP 모뎀 통합에 숙련된
실무형 임베디드 네트워크 엔지니어.

그는 듀얼 W5500, 4G PPP, Wi-Fi AP, NAT/브리지까지
상용 라우터 구조를 MCU에서 완성도 있게 재현했으며,
이는 W5500 기반 설계의 확장성과 생태계 활용 가능성을 실제로 입증.