Hi @facundo.n.r ,
I discussed this with the team and we expect that both ethernets should work independently without issues.
Can you please compile this tool into your system and execute some tests communicating with the PHY? You can find this example explaining how to execute.
Please try to communicate with the PHY after removing the first ethernet, if the PHY reports link down even with the cable connected, we would suspect some issue with the hardware.
Please let me know if you have any doubts.
Best regards,
Daniel Morais