I live in Japan and I have fiber optic internet. I'm thinking I'd like to replace the hardware my ISP gave me, however unlike ASDL, you can't just jump on Amazon to order a modem/router of your choice if you don't like the one your ISP provides, since there's no where to plug the fiber cable in! So this is what my setup looks like at the moment. The fiber cable coming from the wall is plugged into my ISP's box-thing (they call it an "ONU") like this'
From there, I have a ethernet cable going from my ONU to my router.
However this setup still requires me to use my ISP's hardware, and I also suspect that this might be hampering my internet speed. My ISP says I have a 2 gigabit connection, but from what I can see, my ONU only has a 1 gigabit ethernet connection. When I run an online speedtest, it always seems to consistently max out at 947mbps, I think it's really odd I'm always getting that exact number, so I'm thinking that the issue isn't my ISP, but my hardware. That's why I think if I were to replace my ISP's ONU with one that supports 10gigabit or 2.5gigabit, I might see an improvement in speed.
The issue is, I really don't know a lot about fiber optic network hardware. I've had a look around on Amazon, it seems like what I might need is a "optical line media converter". These seem to be for converting from a fiber connection to RJ45 ethernet. From what I can see, the majority of them have a double connector ("single mode" and "multi mode" I think they're called..?) but my ONU only has one plug, so do I just use one of the plugs and ignore the other..? From what I've been able to work out, I'm using an "SC" connector, it looks like this:
The other issue is all the optical media converters I've seen only support 10/100/1000 ethernet speeds, do they not make anything faster than gigabit?
So, is there anyone who can help me untangle this?

From there, I have a ethernet cable going from my ONU to my router.
However this setup still requires me to use my ISP's hardware, and I also suspect that this might be hampering my internet speed. My ISP says I have a 2 gigabit connection, but from what I can see, my ONU only has a 1 gigabit ethernet connection. When I run an online speedtest, it always seems to consistently max out at 947mbps, I think it's really odd I'm always getting that exact number, so I'm thinking that the issue isn't my ISP, but my hardware. That's why I think if I were to replace my ISP's ONU with one that supports 10gigabit or 2.5gigabit, I might see an improvement in speed.
The issue is, I really don't know a lot about fiber optic network hardware. I've had a look around on Amazon, it seems like what I might need is a "optical line media converter". These seem to be for converting from a fiber connection to RJ45 ethernet. From what I can see, the majority of them have a double connector ("single mode" and "multi mode" I think they're called..?) but my ONU only has one plug, so do I just use one of the plugs and ignore the other..? From what I've been able to work out, I'm using an "SC" connector, it looks like this:

The other issue is all the optical media converters I've seen only support 10/100/1000 ethernet speeds, do they not make anything faster than gigabit?
So, is there anyone who can help me untangle this?