Here the issue I am facing:
Newly renovated bungalow with 4 new wired Ethernet sockets / points. Currently ISP modem/router placed in utility room. Central heating system + alarm system control(s) also in utility room and connected directly to modem/router Ethernet ports. So far so good.

I have now upgraded my internet connection to high speed (300mb) FULL optical fibre with a different ISP. However, due to the delicate nature of optical cables which should not be bent, the new ISP installed the new ‘Linksys’ router and the separate optical fibre modem in the dining room right next to the window but fortunately also right next (5”)to an Ethernet wall socket which is currently still wired/connected to the old router in the utility room.

The issue I am facing now is how to switch from the old modem-router in the utility room to the new Linksys router in the dining room, the problem being that all the Ethernet / network wiring are running to the old system in the utility room (quite a distance from the new optical fibre installation). Could I possibly run a CAT6 Ethernet cable from the adjacent Ethernet socket to the optical fibre modem effectively using the OLD modem/router in the utility room as a switch?
If so, I then could leave all the current port connections as they are……

Hence in a nutshell, I am currently running on 2 ISPs: the old broadband router/modem with all the aforementioned devices still connected including Ethernet sockets PLUS, in addition, the NEW high-speed optical fibre Linksys installation for computers / mobiles and some smart home accessories but using only the WIRELESS function currently as all the Ethernet connections are still via the old modem/router (utility room).

Apologies for the lengthy outline and your thoughts appreciated.

  • 6
    Before getting into your question I have to comment that your new ISP installer did a lousy job. "The nature of optical cables" has nothing to do with it. They should have installed their modem, properly, without damaging their cables, where you wanted it. They were lazy. If, in addition to the problems you describe, you just don't want this gear in your dining room, you should call them back to do it right.
    – jay613
    Commented Jan 11, 2023 at 15:45
  • 1
    I’m voting to close this question because it's not about DIY Home Improvement (and my suggestion to migrate to SuperUser was declined).
    – brhans
    Commented Jan 12, 2023 at 14:07
  • Leaving aside the crappy location of the new modem, I don't see a reason you couldn't use the Ethernet run from the dining room to the utility room to pass internet traffic to your existing modem, which would then pass traffic to the other 3 ports. Assuming your router in the utility room has a built-in switch (most do nowadays).
    – Huesmann
    Commented Jan 12, 2023 at 14:46
  • @Huesmann Pass to the existing router in utility room... not existing modem, right?
    – gnicko
    Commented Jan 12, 2023 at 17:44
  • 1
    @Huesmann Just pointing out the details, not not the typo. All good.
    – gnicko
    Commented Jan 13, 2023 at 2:30

4 Answers 4


This had absolutely nothing to do with optical fiber bend radius (it really isn't that bad even with the standard fiber). It has everything to do with either a contract installer paid by the job (so the faster they get it done, effectively the more money they make) or an ISP employee under pressure to get the jobs done faster (more profit for the ISP). But what's done is done. While moving copper (Cat 5/5e/6) is relatively straightforward, optical is a bit trickier, especially if you don't have the right tools and experience, and if anything goes wrong the ISP will not be happy about fixing it. So you leave the fiber where it is, and that means leaving the optical modem where it is.

Three options:

  • Move everything but the optical modem

Connect an Ethernet cable from the modem to the wall jack. Move the Linksys downstairs in place of the old router/modem. Plug everything downstairs into the Linksys. If possible, configure the Linksys to mimic the old router as much as possible (SSID, WiFi access details, gateway, subnet, DHCP range) so that you don't have to reconfigure much of the existing equipment.

The one big drawback of this setup is that now you don't have a usable Ethernet connection in the dining room. Which means either running a new cable (level of difficulty unknown) or using WiFi for that location.

  • Keep optical modem and Linksys in the dining room, use old router

This only works well if the existing router/modem uses an Ethernet WAN connection. If it is a true modem using a coaxial cable or DSL or similar then this method won't work.

Connect from one of the ports on the Linksys to the wall jack. Connect from the wall jack to the router/modem as the WAN connection - i.e., in place of the original ISP's connection. Configure the router to use DHCP to get IP details from the Linksys. Ideally, configure the Linksys to use IP settings that allow the existing equipment to connect without changing settings (can get a little complicated). Change the Linksys WiFi details to match the old router and disable the old router WiFi or keep them as two separate WiFi connections with different SSIDs. Plug the dining room existing equipment into the Linksys.

  • Keep optical modem and Linksys in the dining room, install a new switch

This is my preferred method, though it does require one new (inexpensive) piece of equipment.

Connect from one of the ports on the Linksys to the wall jack. Connect from the wall jack to a new switch (any 8-port gigabit switch will do, such as this TP-Link from Amazon). Plug everything downstairs into the new switch. If possible, configure the Linksys to mimic the old router as much as possible (SSID, WiFi access details, gateway, subnet, DHCP range) so that you don't have to reconfigure much of the existing equipment. Plug the dining room existing equipment into the Linksys.

  • Hopefully an ethernet connection in the dining room is not high on the priorities list.
    – jay613
    Commented Jan 11, 2023 at 16:03
  • And if you do need an Ethernet port in the dining room, they make micro switches that fit in an outlet plate. There might be some goofiness needed with a VLAN for the modem to router connection, but it's all possible and doable for someone experienced with networking.
    – KMJ
    Commented Jan 11, 2023 at 16:44

You will have to check whether the router can operate as a switch. Otherwise you will need to acquire a switch. Gigabit switches are not that expensive depending on how many ports you need.

But otherwise the plan of using the ethernet cable between the fibre modem to the utility room and using a switch in the utility room is solid.

  • some modems can operate in pass through mode, and then all you need is a good patch cable. But you want to see how fast your upstream connection vs your house wiring -- no point in paying for super-fast connectivity that you can't use.
    – gbronner
    Commented Jan 11, 2023 at 15:55
  • 1
    I thought about mentioning that, but he talked about using the new modem's wifi already and doing that would require disabling that as an access point and that assumes the old ISP's router has a ethernet wan port instead of whatever else the old ISP used to the house. A switch in the utility room is the simpler option. Commented Jan 11, 2023 at 15:59

I think you should call the ISP back to install their modem where you want it, as I described in a comment. But if you accept the installation the way it is here is what you can do.

I assume you want to cancel the old ISP right?

I assume you want or need the ethernet jacks throughout the house to work. Do you? You could just use the new ISP's WiFi router and that might be all you need. Or you could by a WiFi mesh system or whatever. I don't generally recommend people using in-wall ethernet wiring for typical residential use. If you have a game console or a file server that needs it, you use one cable for that. But anyway, how to get all your jacks working again ....

  1. You say the new router is next to an existing network jack. So you don't need to run a new cable. Just use the one that's there. Plug the router's LAN ethernet port, with a patch cable, into the wall and in the utility room, plug that port into a switch, and plug all the other outlets into that switch too.

  2. Don't use the old ISP's router as a switch. It might work, but if it's also their modem you're better off buying a switch of your own. An 8-port unmanaged switch is cheap and reliable. Just buy one.

  • 1
    * I don't generally recommend people using in-wall ethernet wiring for typical residential use.* - why not? I think most people don't because they have no idea it is available and/or at a reasonable cost. The cost varies a lot depending on accessibility. Not an option if you rent an apartment. But if you own, the investment can be well worth it. Commented Jan 11, 2023 at 16:55
  • @manassehkatz-Moving2Codidact because it adds complexity, and for most people who don't know how to manage and maintain it, it reduces reliability and adds no tangible benefit in speed or capacity for most typical residential uses. Predicated on a good WiFi network of course.
    – jay613
    Commented Jan 11, 2023 at 17:38
  • 1
    But I could argue the other way. Particularly since wired is set-it-and-forget-it. As opposed to WiFi were numerous software issues - reset router, new router, interference from new neighbor's router, etc. can all get in the way. As far as speed, wired correctly you can get consistent gigabit speed with wired, not nearly as consistent with WiFi. Of course, you could (correctly) argue that almost no residential applications actually need anything near gigabit speed...so then why are Comcast, Verizon, etc. making a big deal about speed? (Answer: marketing, nothing to do with real needs.) Commented Jan 11, 2023 at 18:01
  • @manassehkatz-Moving2Codidact Yes the telcos plug unnecessary bandwidths to home users. My caveat about "no ethernet" is that if you have a game console or a file server (say for an architect or video editor) then you hard-wire those. But most of the stationary devices that most people have in their homes are ones that don't need higher speeds or capacity. A decent wifi network (e.g. a couple of Eeros) can easily handle a bunch of 4k TVs and a couple of Zooms. They can easily handle all WiFi traffic that would consume the entire ISP bandwidth.
    – jay613
    Commented Jan 11, 2023 at 19:07
  • 1
    We had the bungalow extensively renovated, a new large extension built and completely re-wired. Hence adding Ethernet cabling throughout the property was a opportunity not to be missed. My wife and I both work from home most of the time which involves lots of video calls and conferences etc. A stable and reliable high speed connection is therefore essential. I’ve now decided to go for the suggested ‘switch’ option which appears to be straight forward. Many thanks to all the people who commented and put me in the right direction. Very much appreciated! Commented Jan 11, 2023 at 23:27

Step 1: Identify which jack in the utility room the kitchen ethernet outlet connects to. You can use simple lan cable tester to verify all pairs are intact, or just connect a laptop, verify link comes up as 1 gbit, then disconnect cables in the utility room switch until you find the one that cuts the connection. Mark the cable.

Step 2: In kitchen, connect the output ethernet port of new modem to the kitchen lan outlet.

Step 3. In utility room, connect the newly identified cable to WAN port of your router. This will be the port your old ISP modem was plugged into. If you don't have router, or it was an old ISP router you have to return, connect the cable to your switch instead.

Step 4 (optional): Configure the network. Some ISP allow only one computer to be connected to their modem and will ask for device MAC address and set it in their modem. To connect router, go into router settings, find the MAC adress override for WAN port and set it to whatever device your new ISP configured as allowed. The internet should start working by wire then.

Step 5: Test the internet & enjoy.

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