LAN8720Ai Not working

I have been using LAN8720A-i Microchip ethernet IC for my hardware board which is interfaced with PIC32MZ2048EFG100 for one of my project.
For testing, total 7 Boards are designed and out of 7 only 5 are working fine. Remaining two boards are facing issue of LAN8720A-i(reason is unknown). Though hardware section is verified. The LED is not blinking in the connector and no ethernet IP is detected. Also giving stack initialization failed error.
I verified by replacing LAN8720A it worked fine. But with LAN8720A-i it did not work.
 
Please provide me details of how to debug this issue.