DNS Error 202 over ETH with W5500
The user is using an ESP32-S3-WROOM-1 with a W5500 Ethernet module and the goal is to perform HTTPS POST requests and run a web server over Ethernet.
What the User Did
The user is using an ESP32-S3-WROOM-1 with a W5500 Ethernet module (via SPI) on a “lite dev board.”
Main goal: perform HTTPS POST requests and run a web server (also toggling an LED), over Ethernet instead of WiFi.
⚠ Problem Observed
Ethernet connection seems to work at a basic level:
Link UP, IP is assigned (192.168.0.20)
Gateway, mask, etc. correct.
But when attempting to resolve DNS (e.g. www.utr-control.com), they get “DNS resolution failed, error code: 202”.
The HTTP POST fails because DNS can’t resolve the hostname.
Additional Details
The user uses static IP configuration.
They also try setting DNS servers manually (for example, 1.1.1.1, fallback 8.8.8.8) in the network interface settings.
Despite correct link and IP status, the system still can’t resolve hostnames.
Discussion / Possible Causes
From comments and what the user tried:
Could be related to the DNS server setup (maybe upstream router or ISP DNS block).
Maybe the W5500+lwIP stack configuration (or ESP’s DNS/lwIP settings) has bugs or missing configs.
Possibly TLS configuration related to HTTPS (hostname verification etc.), but here the first issue is that DNS doesn’t resolve at all.
Static vs DHCP behavior might differ; using static with manual DNS may have missing parameters.
✅ Key Takeaways
Just having Ethernet connected and an IP doesn’t guarantee full network capability—DNS resolution is critical and needs correct configuration.
W5500 + ESP32 can handle link/IP, but DNS + HTTPS adds more dependency on network stack and DNS upstream.
Users need to explicitly configure DNS servers if static IP, and possibly verify proper lwIP / ESP configuration related to DNS.