Hello, I have deco M9 and switch as TL-SG3428X and TL-SG108E, i have a loop between and unstability (processor a 90%) wifi deco and RJ45 wired cable, how to enable the wire cable, i see on the chat is

Hello, I have deco M9 and switch as TL-SG3428X and TL-SG108E, i have a loop between wifi deco and RJ45 wired cable, how to enable the wire cable, i see on the chat is that Deco M9 not detect the black