> Is there an advantage to using your own ONT

Some customers might want a dedicated ONT, some might want an SFP+ module, some might want one integrated into their router.

Some ISPs only allow registering one ONT per account and don't allow changing ONT serial. With your own ONT you can have a hot spare available if one fails.

Some ISPs restrict access to ONT information, with your own ONT you can log connection quality data into grafana and setup alerts.

The ONT is directly accessible from the ISP's network, some ISPs haven't provided updates for their ONTs since 2016. With your own ONT, you can ensure you're always patched and secure.

I'm not on PON, but on DOCSIS cable, the advantage to using my own modem is:

1. When it breaks, I don't have to wait for weeks for the cable company to send someone to replace it. I just keep a spare on my shelf and can be back up in minutes.

2. Cost: buying my own pays for itself in 6 months.

3. Disintegration: This is more recent, but I've heard from neighbors that the cable company lately doesn't want to rent a modem, only an integrated WAP/router/modem.

Sorry for the late reply, but very often the provider equipment is not great. E.g. with my provider it's kinda random if you get a Genexis or Nokia ONT and people have a lot of issues with Genexis ONTs. I think it is because with the relatively low subscription fees, a more expensive ONT eats out of their fees. In fact, our ISP uses the same FRITZ!Box 5590 that I use for business customers.

There may also be a latency benefit of using a device that is an ONT/modem/router in one. It's one ethernet hop less, but I haven't measured.

tl;dr: when you use your own ONT, you have a choice of picking a known-reliable option.