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AC86U Wan Port only 100 Mbps / WAN DHCP Does Not Function Correctly

Discussion in 'Asuswrt-Merlin' started by ThermoNuke, May 20, 2019.

  1. ThermoNuke

    ThermoNuke New Around Here

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    Two issues I could use yalls help figuring out.

    #1) WAN port only negotiates 100 mbps. If I move the cable modem directly to the PC, I get 1gbps. If I move the modem to a LAN port on the router, I get 1gbps. Put it back on the WAN port, 100mbps. Any suggestions? AC86U on 384.11_2, modem is an Arris SBG6700. I've also tried 3 different known good cables.

    #2) I continue to get the "Your ISP's DHCP does not function correctly" disconnects. Any suggestions? Tried setting wan DHCP to both normal and aggressive but no change.

    Thanks in advance.
     
    Last edited: May 20, 2019
  2. skeal

    skeal Part of the Furniture

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    Try flashing to stock firmware, if the problem persists, I would say a hardware problem specifically the port on the router.
     
  3. L&LD

    L&LD Part of the Furniture

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    #1) Try a cheap switch in between the WAN port and the modem. Also, try a different brand of Cat5e Ethernet cable or better, if the ones you did try were all the same brand.

    #2) Power down your entire network, including the modem, wait at least 10 to 20 minutes before plugging in just the modem, waiting for 5 minutes, then powering up the router, waiting another 5 to 10 minutes, then powering on the rest of the devices.


    Related to #2) above, when was the last time you did a full reset to factory defaults followed by a minimal and manual configuration to secure the router and connect to your ISP? If it has been more than three versions of firmware ago, even if it is a new router, that would be the next step I would be taking.

    Please see the M&M Config link in my signature below for more details on how you can get your router back to a good/known state (it may even help with #1) too). :)
     
    Dave Parker and skeal like this.
  4. Martineau

    Martineau Part of the Furniture

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    What do the following show?
    Code:
    ATE Get_WanLanStatus
    
    ethctl eth0 media-type
    You could try setting the speed manually by selecting your desired speed from the list of 'ethctl' options
    e.g.
    Code:
    ethctl eth0 media-type 1GFD
     
    skeal likes this.
  5. ApexRon

    ApexRon Very Senior Member

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    Excellent job of problem determination! The WAN port is a LAN port from an OSI Layer 1 perspective and should negotiate the same speed unless a higher layer is impacting that negotiation. Enter "Your ISP's DHCP does not function correctly". While the issue could most certainly be the ASUS, I believe the more likely explanation is that your ISP doesn't like a cascaded router. I have seen negotiation issues on the WAN port of an ASUS but never one that also had an ISP DHCP issue.

    I have an AC86U running 384.11 connected to my personal Netgear CM600 to my ISP, Spectrum cable, and never had an issue like you are experiencing. This across many firmware versions, both ASUS and Merlin.

    If the Arris belongs to your ISP I would ask them to change it out with another of a different brand. Most cable ISP support multiple brands of cable modem. The other issue is whether or not your ISP supports cascaded routers. Who is your ISP?
     
  6. skeal

    skeal Part of the Furniture

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    Are you saying he is behind a double nat?
     
  7. Smokindog

    Smokindog Regular Contributor

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    I see you've listed the different connection configurations and the link speed reported but there's one thing I don't see explicitly stated and, even though it's unlikely, I wanted to ask. Are you using a cable that tested out to 1Gb when you plug your router into the ISP router? I've many times found a simple issue with a cable as the root cause.

    Also, are you setting your ISP router up as a bridge or doing double NAT? I've had in the past an ISP device that would only connect at 100Mbs if in bridge mode. I use double NAT and have for years. It simplifies things as well when/if I need to call the ISP for issues.
     
  8. skeal

    skeal Part of the Furniture

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    As suggested above, check the link state of the WAN port of the router, when connected to different devices.
     
  9. ThermoNuke

    ThermoNuke New Around Here

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    ATE returns : W0=M;L1=G;L2=X;L3=X;L4=X;

    Setting "ethctl eth0 media-type 1GFD" causes the link to go dead until I set it back to auto.

    Also back to stock firmware, still stuck with 100mbps.
     
  10. ThermoNuke

    ThermoNuke New Around Here

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    I have.

    Actually yes I am currently running in bridge mode as far as the cable modem goes with the router receiving the public IP.
     
  11. ApexRon

    ApexRon Very Senior Member

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    There are two ports on the Arris, so double NAT is a possibility. I have run my ASUS in a double NAT configuration with no issue but that was with AT&T U-verse (vDSL). Consequently, I don't believe this is a double NAT issue.

    In my 44 years of networking experience, I have never had to scope/trace the exchange between an ISP/Arris and an ASUS router. So I cannot pretend to know how an ISP connection knows the downstream device is a router. However, I do know that years ago some ISP would test connections at o'dark thirty over a weekend and if they found an unsupported device that the customer was not supposed to have, they would shutdown the service. The owner of this post needs to research with their ISP or give us more information about who their ISP is so that someone in country may relate their experiences with said ISP.
     
    skeal likes this.
  12. ApexRon

    ApexRon Very Senior Member

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    Please configure to be used in router mode, not bridge. Nothing wrong with double NAT. I believe @Smokindog found the issue.
     
  13. Smokindog

    Smokindog Regular Contributor

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    Try using double NAT to see what happens.
     
  14. Martineau

    Martineau Part of the Furniture

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    OK, whilst auto-negotiation in GigabitEthernet is standard for both ends, it was worth a shot.
     
    skeal likes this.
  15. ThermoNuke

    ThermoNuke New Around Here

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    Just factory reset the cable modem and left it in routed mode. Unfortunately the AC86U is still only getting 100mbps on the WAN port. Went from modem to PC and got 1gbps. I even broke out my laptop, plugged it in to the wan port of the router, still only 100mbps.

    Sounds like I'm going to have to send the router back.
     
  16. L&LD

    L&LD Part of the Furniture

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    Try a cheap GbE switch between the WAN port and the modem. Easy check. ;)
     
  17. Smokindog

    Smokindog Regular Contributor

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    Did you also factory reset the AC86U? Start fresh from scratch.

    1) reset both ISP router and AC86U
    2) set up the ISP router
    3) connect laptop/PC to LAN port of ISP router
    4) verify speed
    5) using same cable and same port connect WAN port of 86U to LAN port of ISP router
    6) verify speed

    If it fails speed test, repeat the process with second cable, especially if these are homemade. Some RJ45 ends don't play nice. I make most of my own cables and have experienced connection issues with certain makes/batches of connectors which can be exacerbated by your crimp tool.

    It's just one of those things. Remember, all these consumer devices are working to use the lowest cost parts/pieces :)
     
  18. ThermoNuke

    ThermoNuke New Around Here

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    Its got to be something wrong with the router physically. I turned on dual WAN and set port 4 on the LAN to be the new WAN port. Internet is up and its negotiated a 1gbps link.

    Something definitely broke with the physical WAN port.
     
  19. skeal

    skeal Part of the Furniture

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    This does in fact point towards a port issue but seriously you should reset to defaults as suggested in the post by @L&LD
     
  20. ThermoNuke

    ThermoNuke New Around Here

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    Sorry, I may have forgot to mention it, but I already had. Both the router and cable modem, even re-flashed factory firmware and reset.
     
    skeal likes this.