I bought an ASUS RT-AX86U Pro and want to use it instead of my ISP router.
The problem is that the cable in the image below is connecting to my router, and the ASUS one has no input for such cable:
What is this called?
Can I find some adapter from this type of cable to RJ45 which the Asus Router supports.
It is a 'standard' single-mode fiber cable with an SC-APC connector at the end. It's meant to connect to an ONT or ONR from your wall.
You can't 'really' connect it directly to a random consumer router in most cases - it's meant to go into an optical fibre device. Most ISPs use a GPON or XGPON protocol - which is either supported by your ONT/ONR natively or from a specific type of SFP/SFP+ module (distinct from the common variant used in LANs). Your consumer router is unlikely to have either, and even if you got the 'correct' module, you'd need to talk to your ISP about setting it up.
With my parents' ISP, who supply an ONR (Optical network router, where the network edge device provided by the ISP also acts as a router), I set up a DMZ to my own router to use it as the main router (bridging is the 'correct' option but not documented or supported by the ISP) - which is probably the simplest way to 'semi' bypass the router. Alternatively you can leave it as a router and run your Asus in AP mode for wireless and more ports.
Be very careful. You seem to be in way over your head and could get in serious trouble with your provider if you get this wrong.
As the other answer has said, that is a SC connector with "angle polished" (APC) mating surfaces. A connector widely used by telcos for single mode fibre. There are technical pros and cons to flat polish verses angle polish but they aren't hugely relevant here other than to say that flat polish is more common in the computer networking equipment world, while angle polish is more common in the telco world.
Mating an angle-polished connector to its flat-polished (PC, or UPC) counterpart will result in high signal loss and can damage the mating surfaces of the connector. So angle polished connectors are colour coded green to reduce the risk of accidental mismating.
But the more serious issue here is that most fibre to the premises "broadband" services are based on passive optical network (PON) technology. One port on the equipment at the telephone exchange serves multiple customers (potentially as many as 64, though in practice probably less), though a passive optical splitter/combiner located close to the customers. This saves both ports on the exchange equipment and fiber in the ground, while avoiding the reliability issues inherent in operating active equipment in street-side cabinets.
But it also means that use of the correct equipment on the customer side is vital. If inappropriate equipment is connected then there is a risk that it not only fails to establish a link, but also knocks out all the other subscribers on the same splitter.
And even if the equipment you have is compatible on the protocol level, it must be correctly configured to authenticate to the equipment at the service provider.
As others have said, this connector is only supposed to be plugged in to the equipment your ISP provided.
Check out the detailed manual for the ISP router. With luck you will be able to put it into some kind of "passthrough" mode in which it doesn't act as a router at all, but just does the optical - Ethernet conversion that you want. Then you can plug your own router in to the ISP router, and you are all set.
The details depend on your ISP and the router they have supplied to you, so its difficult to give more advice without knowing that. But for example, here is how to do it for Verizon's router.
