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Force 100Mbps by Crimping Only 2 Cat5e Pairs?

  • 27-08-2019 12:09pm
    #1
    z0oT
    Registered Users, Registered Users 2 Posts: 740 ✭✭✭


    Can 100Mbps instead of 1Gbps be forced by crimping a cable and just connecting two of the twisted pairs? Curious as I haven't ever tried this before.

    Background - My ISP is a fixed wireless provider whereby there's a dish on the roof. I'm having some issues lately with the WAN connection on my Router being dropped. My ISP would have provided me with a cheap Router with just 10/100 LAN, including the WAN port.

    I've changed to a better Router, where all the ports are 10/100/1000 capable. Since the Router change, I've noticed sometimes that the Auto-Negotiation speed of the WAN port in the new Router can vary between 100Mbps and 1000Mbps after it goes down and comes back up later. I'm wondering if I can force 100Mbps on the WAN port would it solve the issues, given the old Router with only 10/100 ports didn't have these issues.

    My desire is to have 1Gbps on the local LAN for file transfer speeds, but I don't really care about the WAN port operating at a lower speed since we only have a 50-60Mbps connection anyway.

    There's no capability to force the WAN port to operate at 100Mbps in the Router WebUI, so I'm curious if it can be done by the cable instead.


Comments

  • #2
    trompele
    Closed Accounts Posts: 129 ✭✭trompele


    Yes,
    Crimp only cables 1,2,3,6 (usually White Orange, Orange, White Green, None, None, Green, None, None).


  • #3
    z0oT
    Registered Users, Registered Users 2 Posts: 740 ✭✭✭z0oT


    Okay that's worked, WAN port is now Auto Negotiating at 100Mbps only - Thanks.

    Hopefully it'll solve the Router WAN connection issues.


  • #4
    KeRbDoG
    Registered Users, Registered Users 2 Posts: 4,322 ✭✭✭KeRbDoG


    Great to hear this is sorted but most routers would have an option to set the speed of its WAN port from Auto to 10/100/1000 depending on need. This wasn't the case?


  • #5
    Cuddlesworth
    Registered Users, Registered Users 2 Posts: 14,010 ✭✭✭✭Cuddlesworth


    If the port speed was going from 100 to 1gig, then there was a fault in the port or the cable between them. You didn't fix the issue, you went round it.


  • #6
    z0oT
    Registered Users, Registered Users 2 Posts: 740 ✭✭✭z0oT


    KeRbDoG wrote: »
    Great to hear this is sorted but most routers would have an option to set the speed of its WAN port from Auto to 10/100/1000 depending on need. This wasn't the case?
    My router doesn't have that capability, at least not that I can find. Custom firmware might work but I'm not a fan of going down the road of flashing custom firmware.

    Gimping the cable was the easier option.
    Cuddlesworth wrote: »
    If the port speed was going from 100 to 1gig, then there was a fault in the port or the cable between them. You didn't fix the issue, you went round it.
    Yes, more than likely.

    My ISP is a wireless ISP. The WAN port of the Router is connected via a PoE injector to a dish up on the roof via ~20m of weatherproof Cat 5e cable. The Router the ISP supplies only has 10/100 capable ports.

    Since the Router upgrade, usually the connection would auto-negotiate at 1Gbps, work for a few days, then be dropped only to come back up at 100Mbps. Causes me to suspect that there might be another reason other than cost that they chose that router to supply to customers.

    Either way, it seems to have solved the issue now.


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  • #7
    KeRbDoG
    Registered Users, Registered Users 2 Posts: 4,322 ✭✭✭KeRbDoG


    z0oT wrote: »
    My router doesn't have that capability, at least not that I can find.

    Good to hear the cable mod did the trick - I'd be interested to see what router you have though if you could share?


  • #8
    smuggler.ie
    Registered Users, Registered Users 2 Posts: 4,227 ✭✭✭smuggler.ie


    z0oT wrote: »
    My ISP is a wireless ISP. The WAN port of the Router is connected via a PoE injector to a dish up on the roof via ~20m of weatherproof Cat 5e cable. The Router the ISP supplies only has 10/100 capable ports.

    Since the Router upgrade, usually the connection would auto-negotiate at 1Gbps, work for a few days, then be dropped only to come back up at 100Mbps. Causes me to suspect that there might be another reason other than cost that they chose that router to supply to customers.
    As per Cuddlesworth comment, if you get 1000Mbps, it indicates hardware is capable to run it. Drop out could indicate other issues - water/dampness/corrosion/fault on dish unit/cable.

    Once you already have skill crimping your own cable, you could replace(even with ordinary CAT for, few days) that 20m run and see if it makes difference, if you will.
    If its capable - why not to have it.

    Again, if you happy with 100Mbps on WAN, let it go.
    history of boards 2021




  • #9
    z0oT
    Registered Users, Registered Users 2 Posts: 740 ✭✭✭z0oT


    KeRbDoG wrote: »
    Good to hear the cable mod did the trick - I'd be interested to see what router you have though if you could share?
    It's a Tp-Link AC1750 Archer C7.
    smuggler.ie wrote: »
    As per Cuddlesworth comment, if you get 1000Mbps, it indicates hardware is capable to run it. Drop out could indicate other issues - water/dampness/corrosion/fault on dish unit/cable.

    Once you already have skill crimping your own cable, you could replace(even with ordinary CAT for, few days) that 20m run and see if it makes difference, if you will.
    If its capable - why not to have it.

    Again, if you happy with 100Mbps on WAN, let it go.

    To do that would require routing through the attic and climbing up on the roof.

    I've no problem crimping or punching down either Cat5e or Cat6, but given I'm not familiar with the dish on the roof, I'm not sure how I would connect the new cable to it. I'd have to clamber up there and take a look at it - although it's got to have an RJ45 or a Keystone jack somewhere.

    Forcing 100Mbps on the WAN has solved everything - 100% uptime for a number of weeks now. Being an Engineer, usually I'd like to understand these things but in this case I'm happy to accept it and move on - our connection is 50-60Mbps max anyway.


  • #10
    z0oT
    Registered Users, Registered Users 2 Posts: 740 ✭✭✭z0oT


    Cuddlesworth wrote: »
    If the port speed was going from 100 to 1gig, then there was a fault in the port or the cable between them. You didn't fix the issue, you went round it.
    Just an update on this in case anyone is interested.

    After creating a cable forcing auto negotiaton over the WAN port of 100Mbps speeds only, the WAN drop outs started returning again after a few weeks. I was consistantly getting that "WAN cable is unplugged" message once more, when it clearly wasn't and the ISP wasn't reporting any downtime.

    Well now I believe the issue is buggy firmware from TP-Link. I have V4 of the router, but if you look at the V5 firmware update release notes, there's a fix listed for instability of PPPoE connections, which is what I use with my ISP. However there is no such fix for the V4 version.
    https://www.tp-link.com/uk/support/download/archer-c7/v5/#Firmware
    https://www.tp-link.com/uk/support/download/archer-c7/v4/#Firmware

    What I've done now is flash the router to DD-WRT firmware which seems to have solved the issue since it's been well over a year and there's no fix from TP-Link in sight.

    I'm now getting uptime of 24hrs on the PPPoE connection. It seems to reset each night at midnight, which I suspect is an ISP thing. The previous TP-Link firmware didn't even have a way to monitor the uptime of the PPPoE connection.

    The Archer C7 consistantly had good reviews from lots of tech sites. It was recommended as a good budget option. The WIFI strength is good throughout the house, and I particulary liked the ability to host an OpenVPN server on it, I was able to delete a number of port forwardings as a result. I've got an OpenVPN server working on DD-WRT now, but it was quite a bit more involved to set it up.

    I should probably switch the WAN back to 1Gbps as a result now.

    The issues I've had with the Archer C7 would be:
    • Random WAN connection dropouts - The worst one of all
    • Laggy Web GUI
    • System Time constantly being wrong despite manually setting it or supplying it with a time server
    • Reboot schedule not working
    I guess it's a lesson not to buy a TP-Link router again, despite what reviews might say.


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