I am having a problem where the ethernet on my gateway goes down constantly and the gateway becomes unreachable for a short time then comes back. I get a "This page is not working" or unreachable error.
I have swapped the cable and the port on the switch and see no difference. IP address is static.
first shot is MQTT server. Do you have it running in your network? And is it properly configured in OHS? It is normal behavior of OHS, if it does not find MQTT server it resets its own Ethernet driver periodically.
On web interface, tab Network, you can check the status and also change the IP and port.