ORBI 350 BAD Internet from LAN Ports

Hello

I purchased a RBR350 plus Satellite RBS350

I followed the instruction for substituting the Vodafone Router (FTTH with Fiber to ethernet converter) and configuring the RBR350 according to the guide, success, I removed the VODAFONE Router.

With the Orbi Android app, I tested the speed on the Orbi RBR350 being 900 Mbps D/L and 200 Mbps U/L

I have very good Wifi from the Orbi, good coverage and speed of 300 Mbps in d/l and 200 Mbps in upload

PROBLEM: I have very bad / no internet from the 3 Ethernet ports of the RBR350, Chrome has big trouble loading pages, a page of a main newspaper takes one minute to load. Sometimes it goes faster, then it goes to zero.

What I have tried:  

- updated Router and Satellite sw to latest version V4.4.0.10_2.10.63

- Tried with 2 different PCs (Same Result) (Laptop workd great through wifi, no page load with ethernet)

- Tried on the 3 different ports (Same Result)

- Tried with different cables (Same Result)

There is no other Router on the network.

Is there anything else to try or I should send it back to Amazon?

Thanks very much

Kind regards

Alessio