We have now confirmed you still experience drop outs even though your device is plugged into the router.
In this step, we need to completely isolate the router from being the issue. This step may require some patience as you will only be able to use one device. If this step is too difficult, select "Yes" at the bottom of this guide.
With your device still plugged into the router, unplug the cable from the back of the router's LAN port and connect this end into the bottom of the ONT which should be attached to the wall where your fibre was installed. Depending on the type of ONT you have, you will need to look for a port labeled LAN1 or GE1.
Connect the ethernet cable to this port. The setup should look similar to this:
Now, test this connection until you would normally notice a disconnection.
Do you still experience disconnection issues on this device?