Omnitik Ether1 restarting continously

Hi, I have omnitik, the interface continuously goes up/down ,every 5-10 seconds.

Not able to login more than 5 seconds. In logs it says LinkUP /DOwn.
What could be the reason. v5.14

Can we downgrade??

did you upgrade to 5.14 ? or what?

Did you upgrade the firmware as well?

/system routerboard upgrade

Are you sure our cable on eth1 is terminated correctly and not past max cat5 length?

It may be because firmware bug and auto negotiations.. when its connected to switch, it works fine.