@KatsB I forgot to add that even with the cable that came in the box, its the same problem.

@ARGamingPK1 Thanks for a quick response, I have changed to different cables but I still get the same issue, For your info my internet is 250Mbps. I may think that it is not a cable problem because...

My internet speed goes down and I get an error message in the App: "Abnormal WAN port speed. Please check your WAN port connection"