[SOLVED] MAC address changes with new Project/new Auth Token on same hardware

Just getting started with Blynk. I’m using an Arduino Uno with the 5100 Ethernet Shield. After the first project assigned a unique Auth Token, I was successful in obtaining an IP address from my router’s DHCP. I created an Address Reservation for theWIZnetAAA6B7 Client as shown below.
When I created a second project (again with a unique auth token) using the same Arduino Uno and Ethernet Shield, not only did I get a different IP address, but the MAC address was also different. The Ethernet Shield’s true hardware address (90-A2-DA-0E-93-XX) is different from either one of the two displayed in the router’s DHCP Client List. Considering that MAC address is supposedly unique, why am I seeing different MAC addresses?

6 WIZnetAAA6B7 FE-87-D4-AA-A6-B7 Permanent
7 WIZnetF8F8BF FE-DF-88-F8-F8-BF 05:38:2

This is not a Blynk relevant issue… rather an issue with the Ethernet Shield as most clones do not contain a “fixed” MAC. There are ways to “assign” your own MAC address to the shield via code.

Google MAC address for W5100



Gunner, thanks for the quick response! I’ll look into your provided link. You said that the issue was with the Ethernet Shield. The one I have is not (or should not be) a clone, since I originally purchased both a genuine Arduino and Ethernet shield. The label on the underside of the shield does give a hardware MAC, but it is totally different than the one(s) displayed in my router. A MAC address lookup of that label 90:A2:DA:XX:XX:XX shows the manufacturer to be:
Company GHEO SA
Address Chiasso CH-6830