RM520N-GL RGMII Ethernet port issues/drops

i have ordered rework board and when load is high, loosing connection. anyone else have same problem? and what configuration to check?

sound like not enough power. what is the power source?

12v 4amp came with zyxel router and using that one. talked with seller too and no idea.

Does it stay available over USB when this occurs?

if i connect usb, connection is gone. but i didnt check if usb is available though when connection is lost. i can give a try.

with mcuzone poe board, i can connect ethernet and usb sametime even enable teetering and no issues.

firmware

AT+QGMR
RM520NGLAAR01A08M4G_01.200.01.200