Ask HN: Why does it seem hard to buy an ONT for fiber?

There are, undoubtedly, many reasons for justifying not having to use their equipment. Besides rental cost, having extraneous hardware which is unused functionality at least raises the probability that there could be something which goes wrong due to added complexity. The most compelling reason being if I insist on using bridge mode(on such a gateway), and then, after some unforseen firmware upgrade, that setting is reset, then my entire network becomes unreachable. Or at least as unreachable as it once was before the update. Having a simple bridge device like a pure modem or plain old ont, there can be no functionality to reset which would potentially alter the state of the netowrk. It either passes as a bridge or it doesnt. A lot of the friction though, at its core is the result of either, drumroll, having full access to the device providing layer 3 NAT or not. As ISPs want to smush together their on premises equipment they, due to the nature of the stack need to take control of the NAT to do so. At that point users who would like to open ports or do anything more than request a connection from the insdide are, out of luck, and it shoulnd't be accepted, as ISPs dont NEED gateways to make thier network work. Illustrated by the many smaller ones who do just fine without.

Mostly because a lot of ISP's serve the ONT as an NTU (IE your network gateway or border) and others use it as CPE.

Here in Aus the (horrifying, terrible) national broadband network uses the ONT as an NTU from which it can split the service out to IIRC 4 ethernet hand offs and 2 RJ11 voip services. And because of this most private fibre providers do much the same. (Although NBN does it in part because their authentication method involves inserting DHCP option 82 into DISCOVER and REQUEST messages) In fact, I am aware of one that has moved to a single port ONT but still provides the customer another router beyond the ONT and keeps the ONT for NTU purposes.

NTU's are good actually, having a device to troubleshoot from inside or very near to the customers premises can keep support costs extremely low. If you have something that can also perform an ethernet cable test so much the better.

That said, there's another possibility. I have seen quite a few ONT's and man the majority of them in the usual price range of a residential ISP SUCK. The interface sucks, the hardware sucks, the software sucks and some of them have a lifespan comparable to a fruitfly. I wouldnt want my customer getting too familiar with devices that look like garbage and can fall over at the drop of a hat. So we just hold on to the password of those and let the customer do whatever they want past the demarc.