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:enter image description here

What is this called?

Can I find some adapter from this type of cable to RJ45 which the Asus Router supports.

  • 2
    it is called what you called it. Why do you want to use your router instead of the one the ISP gave you? That is clearly not an option. You should use both. Just connect your ASUS RT-AX86U Pro to the router the ISP gave you.
    – Gantendo
    Apr 21 at 21:51
  • You mean it is called optic fiber ? I thought it had a codename like "rj45". I knew that my isp uses fibers and i just posted that as info. I need then a optic fiber -> rj45 converter so i plug into my asus "internet" port Apr 21 at 21:54
  • 1
    We usually call them what they are, fiber optic internet cables (you could get more technical than that but thats rarely necessary). There are a few different connectors. Look at the MU here medium.com/@sweetlittledollar/… The RJ45 is not the RJ45 btw flukenetworks.com/blog/cabling-chronicles/…
    – Gantendo
    Apr 21 at 21:58
  • 15
    The router the ISP gave you is the optic fiber -> rj45 converter you are looking for... and its free! Now you just need to connect your ASUS router to the ISP router and boom.
    – Gantendo
    Apr 21 at 21:59
  • 4
    @KristiJorgji: "Media converters" will not work for you, because they deal with a different kind of network; they're made for Ethernet while it's pretty likely that you have GPON, and that needs more than a media converter; it pretty much needs a whole "modem", which is generally called an ONT as in Journeyman Geek's answer. Apr 22 at 7:32

3 Answers 3


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.

  • Thanks. Marked as answer, I googled and find exactly my photo with SC-APC. I will google now for SC-APC to RJ45 adapters Apr 21 at 23:42
  • 20
    They don't exist. In theory, you can use a media converter - but the protocol ISPs use, GPON won't directly map to ethernet
    – Journeyman Geek
    Apr 21 at 23:47
  • 4
    @KristiJorgji, the idea of an "adapter" just isn't a thing for these types of media. the two technologies speak entirely different languages. if you are going to bring your own router to your ISPs party, then you need to show up with a compatible router. Or, as folks are suggesting in the comments, use your new router in addition to your existing one, rather than as a replacement. Apr 22 at 0:25
  • I am shocked the ISP modem doesn’t require a fiber optical module, there probably is one, but it’s transparent to the author
    – Ramhound
    Apr 22 at 1:02
  • 2
    Its not a seperate 'module', its built in
    – Journeyman Geek
    Apr 22 at 1:04

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.

  • 2
    hm.. thanks for the warning. Then I just used my ISP router as a "converter", and used lan-2 port of it to connect to internet port of my AsusRouter serve as WAN.. Apr 22 at 22:22
  • 2
    @KristiJorgji That'll most likely work fine, the thing you want to do (if possible) is configure the ISP router so its DHCP is turned off and it acts as just a transparent network bridge, letting your Asus pick up the broadband IP as its external address. Some ISPs, that's not a self-serve config, you have to request they reconfigure your device. Others, it's not possible at all. But if your Asus router's upstream IP is 10.x.x.x or 192.168.x.x, you're Gonna Have A Bad Time™ with double-NAT woes.
    – FeRD
    Apr 23 at 1:34
  • "There are technical pros and cons to flat polish verses angle polish but they aren't hugely relevant here" s/aren't hugely/aren't even remotely/ #ThereIFixedIt
    – FeRD
    Apr 23 at 1:36
  • To be frank, there is no other answer saying anything about polish angles. The other answer only mentions the abbreviation "APC", but one needs to be in the know or explicitly look it up.
    – ilkkachu
    Apr 23 at 8:38
  • @FeRD Would it not also potentially be feasible for OP to configure the router as, well, a router? No NAT, OP just picks another private subnet for their new router, and routing tables on the two routers are updated to send packets for the relevant subnets to the relevant router.
    – James_pic
    Apr 23 at 9:12

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.

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    – Community Bot
    Apr 24 at 15:38
  • I've updated using Verizon as an example. Its difficult to say anything more general because the details depend on the ISP equipment. There are some more general explainers on the Web, but they muddle it up with bridge mode, which is something different. Apr 25 at 14:23

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