What does this error message means?

Hello Support,

What does this error message means “ether4: bridge port received packet with own address as source address (cc:2d:e0:af:a6:77), probably loop”?
My client called that he was not have a smooth internet connection, I observed that from the MikroTik router log the above warning message. I unplugged one of his wireless access points cat - 5 cable from the mitroTik router and the error message stopped.