My Zyxel T-56 shows all the necessary lights on in green, and the fibre convertor has the POWER, PON and LAN lights on in yellow.
However, all of the devices connected to the router via wifi or directly via ethernet cable are now unable to connect to the internet.
I have not changed or moved any devices in my home.
I've also tried unplugging everything for a minute, then plugged in the fibre converter first, followed by the router a minute later.