Thanks for the Information.
and EMI test failed , it emitted slightly over not too much,
Could you tell us, which frequency value did you see during the tests?
my carrier board has two ethernet and usb, serial , usb is connected to LTE modem
Did you follow well the design guidelines for the carrier board?
a hardware engineer asked me to reduce DDR clk speed
I am sure that reducing DDR clock will not help you.
In the past, we have seen some customers with issues regarding EMI created by Ethernet or parallel Display. In general, you should check also if there is no antenna affect created by the cables, thus you should use proper cabling with shielding if needed.