Honestly, I am uncertain if this DP83867 PHY is able to work here.
This PHY has been tried by some other users before but seems none of them is able to make it work in the end.
Maybe using the Marvell 88E1512 PHY which has been validated by us would be a safer solution.
This user has a tool to locate where is the exact MDIO address running on their board.
Maybe you could refer to this post first