Ethernet port looping it's own TX on RX

I’m having trouble with my RBwAP2ND
After around year of use, the only ethernet port on it stopped working.
By connecting with it to winbox through wlan, I noticed there is the same amount of TX packages as RX.
When I enable the loop protect It shows error about detecting loop on eth0.
On my PC I can the total send/recieved packages shows 4000/0
I’ve tried cleaning the board with alcohol, which didn’t help in any way.
Is it a common problem? does anyone have a possible solution ?
Thanks in advance