Our UFB connection had been reliable (well, mostly) for 12 years across two ISPs but starting 2 months ago there have been outages lasting from a few minutes to several hours. The status pages for both the ISP and infrastructure companies haven't shown any issues so I think it is just our address affected.

During these the router logs show it is retrying to connect, while the Chorus type 100 ONT just has the Power and LAN1 lights lit with the others including Optical and Alarm all off. I've reported a few of these to the ISP whose tests show that nothing is connected at this end. A technician has been scheduled to attend twice but operation has resumed first so I cancelled those as I expected no fault would be found. I wonder if the ONT has reached end of life but don't know of a way to check that.

Any suggestions or advice about how to handle this?