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AC-5300 - No routing between 5G-1 and 5G-2

Discussion in 'Asuswrt-Merlin' started by ryannathans, Mar 21, 2019.

  1. ryannathans

    ryannathans Occasional Visitor

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    Nov 25, 2016
    Messages:
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    Hi all

    It seems that devices on 5G-1 and 5G-2 cannot "see" each other.

    On Wireshark it seems some packets can't traverse from one 5G band to the other.

    Has anyone encountered this issue or got a fix?

    I suspect the same issue exists on other dual 5GHz routers too.
     
    Last edited: Mar 21, 2019
  2. RMerlin

    RMerlin Super Moderator

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    Canada
    Make sure you didn't enable AP isolation.
     
  3. ryannathans

    ryannathans Occasional Visitor

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    I made very sure AP isolation is off for all bands
     
  4. ryannathans

    ryannathans Occasional Visitor

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    I will conduct and document a clear experiment for reproduction
     
  5. ryannathans

    ryannathans Occasional Visitor

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    To me it looks like all packets can go from 5G-1 -> 5G-2 but only ARP requests (not responses) can go from 5G-2 -> 5G-1

    Experiment below:

    RT-AC5300 with smart connect on 5G-1 and 5G-2 (independent 2.4GHz)

    1. Pick one device from 5G-1 and one device from 5G-2
    192.168.0.6 on 5G-1 (DC-85-DE-7D-00-4D)
    192.168.0.162 on 5G-2 (9C-B6-D0-20-45-A3)

    2. Open wireshark on each
    3. Attempt to ping one device from the other

    Pinging 192.168.0.162 with 32 bytes of data:
    Request timed out.
    Request timed out.
    Reply from 192.168.0.6: Destination host unreachable.
    Reply from 192.168.0.6: Destination host unreachable.

    Ping statistics for 192.168.0.162:
    Packets: Sent = 4, Received = 2, Lost = 2 (50% loss),

    4. Collect and compare captures (filter: arp || icmp)

    192.168.0.6:
    [​IMG]

    192.168.0.162:
    [​IMG]

    5. Repeat ping test in reverse

    Pinging 192.168.0.6 with 32 bytes of data:
    Request timed out.
    Request timed out.
    Request timed out.
    Request timed out.

    Ping statistics for 192.168.0.6:
    Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),

    6. Collect and compare captures

    192.168.0.6:
    [​IMG]
    192.168.0.162:
    [​IMG]

    Files: https://mega.nz/#F!NJFgQAzC!ya0nWBt8Bgz0iBijvQbDTg
     
    Last edited: Mar 21, 2019
  6. ryannathans

    ryannathans Occasional Visitor

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  7. L&LD

    L&LD Part of the Furniture

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    What firmware are you running?

    Was a reset to factory defaults performed and then a minimal and manual configuration made afterward to secure the router and connect to your ISP?

    Please see the links in my signature below on details of how to do it properly (M&M Config) can bring your router to a good/known state and proper troubleshooting can be more effective than chasing self-inflicted bugs and glitches like what is reported here.

    The following link shows the importance of doing the steps suggested above.

    https://www.snbforums.com/threads/faq-nvram-and-factory-default-reset.22822/
     
  8. ryannathans

    ryannathans Occasional Visitor

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    I am running the latest at time of writing, 384.10_2.

    Factory defaults were set recently, perhaps two firmwares ago, after attempting to solve this problem myself.

    This problem has always occurred, possibly even between 2.4G and 5G at times. I'm not aware of any configuration, minimal or otherwise that fixes the issue.

    On mobile I can't see your signature, when I'm home I'll have a read.
     
  9. L&LD

    L&LD Part of the Furniture

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    Try holding your phone sideways to see signatures on mobile devices. ;)

    This is not normal... when you did the reset to factory defaults, did you use a backup config file to restore your settings with?

    When you say you're not 'aware' of a minimal or otherwise configuration that fixes this issue, is that from experience, or are you simply stating that you don't know about a process that works?
     
  10. ryannathans

    ryannathans Occasional Visitor

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    Now that's a handy tip.

    When doing a factory restore I make sure previous config files are deleted and not reused.

    I've tried multiple different configurations but haven't found any setting that relieves the issue, it seems like more of a bug at this point.

    At one point lan to wifi on a single device had the same issues but it resolved itself after a few hours, it seems to be just this persisting but I haven't rigorously tested every interface to every interface.

    What do you recommend?
     
  11. L&LD

    L&LD Part of the Furniture

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    Does the issue still persist when, immediately after doing a full reset to factory defaults and only securing the router and connecting to your ISP with no additional customizations or changes past those defaults, you test it then?

    If so, and only if you are truly doing a full and proper reset to factory defaults, then this must be a hardware issue and the only fix is to replace the router.

    What I recommend is to do the following to make sure that the issue isn't a misconfiguration on your end.

    Please refer to the link in my signature to follow more detailed steps of the outline below.

    1. Remove all USB drives and Ethernet cables from the router, including the WAN cable.
    2. Perform an NVRAM erase
      1. By unplugging the power plug from the router (and not from the ac power socket on the wall).
      2. Wait 2 minutes, then, holding the WPS button, plug in the power plug into the router and continue holding the WPS button until the router reboots (about 30 seconds or more).
    3. When the router has booted up (be patient, this may take longer than normal)
      1. Do a quick/temporary wizard set up to gain access to the advanced GUI controls.
      2. Once inside the GUI, select the 'format jffs partition on the next reboot' and reboot the router.
    4. Once the router has booted up again, reset the router via the GUI to factory defaults, making sure to select the box that says 'initialize all settings...) too.
      1. Do another quick/temporary wizard set up to gain access to the advanced GUI controls.
    5. Flash the same firmware you are currently using (384.10_2).
    6. Plug in the WAN cable while the router is rebooting.
    7. When the wizard comes up this time,
      1. use new SSID's with no spaces or special characters that are at least 8 characters long (and no smiley faces).
      2. Make sure the password also has no special characters or spaces and is at least 16 characters long (and no smiley faces too).
    Now, does the above allow clients to communicate between all three bands, including the wired devices?
     
  12. ryannathans

    ryannathans Occasional Visitor

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    Thanks, I'll try that out when I have some time. The default config on a fresh reset doesn't work, by memory the default config on a fresh reset is smart connect. I will try without smart connect too, just separate APs.

    I thought I'd try chromecasting from my phone on 5G2 to my chromecast on 5G1 and oddly enough that works fine, however, from the same device I can't ping my PC on 5G1 until my PC swaps to 5G2. This is with no config changes.
     
    L&LD likes this.