Sometimes NAT Loopback Stops Working

I'm relatively new to Eero.  I have 3 Eero Pro units.  I have several ports forwarded to internal devices and use a dynamic DNS service, and I rely on NAT loopback (I think also called hairpinning) so I only need to use the external dynamic hostname no matter where I am (inside or outside of my network).

Occasionally, from inside the network, I can no longer access those forwarded ports using the external hostname/IP.  From outside the network, it always works fine.  And yes, I'm sure that I'm using the correct external IP.

The strange thing is, the problem pops up and then disappears on its own.  Sometimes it only affects some forwarded ports and not all.  Sometimes the problem only occurs from one device on my internal network and works fine from another.

I had a Linksys Velop mesh wifi system and a few other routers before that which never had this issue.

Any ideas?

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  • This problem was more frequent before some of the firmware releases back in the late summer of 2018.  I RARELY have it happen any longer.  However, I access about 90 internal devices via host names that are resolved externally, and say 1 time out of a hundred I find the ports are blocked these days versus maybe 1 out of 10 in the past.  Rebooting the entire system corrects the issue, but like I said, the issue used to be far more common early last year.

  • I'm having the same problem. It seems like every 3-4 weeks, it starts failing. I have to reboot the routers. I know rebooting the routers is not a huge deal. But it is an issue when other people are using the network. I have to wait until another time to do this. Are there any plans to look into this issue and address it once and for all?

    • Thanks for reaching out schmatt and sorry to hear you're having some trouble here. We're not really aware of any ongoing problems, as such, with hairpin NAT, so this is definitely something we'd like to investigate with you in more detail. If you haven't already, please send an email with the details to support@eero.com and feel free to put "Community feedback" in the subject line and I'll make sure a senior specialist gets eyes on it! That goes double for you, arbies since you're the one who posted this thread! 

      We look forward to hearing from you so we can investigate your network setups and see what additional insights and improvements we can offer!

      Drew, eero Community Team

  • I seem to have this same issue off and on with a QNAP NAS server. Currently trying to find a workaround. 

  • I’m running into this EXACT same issue with my Eero and all right now. I’ve been searching for hours and finally came across your thread and was floored how someone finally described my issue. Does this keep happening? Any further resolution from support, arbies ?

      • arbies
      • arbies
      • 2 yrs ago
      • Reported - view

      Puppy34 it still happens occasionally, but it seems to be less-frequent lately.  According to maxelman it sounds like they're aware of it.

  • Spent 20 minutes on the phone with eero today. The final word was: "engineers are aware of it and we'll keep you updated."

    Time to look at other home networking options. 

  • I submitted a support ticket at eero’s request above. They did evaluate some information remotely both when things were fine and when I started to observe an issue. Ever since then, I haven’t run into the issue. I’m not sure what happened there, but everything is good now. 

  • Drew

    I am also seeing this right now.

    Works fine when I use a different network (e.g., turn on my VPN).


    In the Eero app's advanced networking page, provide a setting called "Test Hairpin" - would this would do is, say,

    1. Set the Eero mesh itself to respond to an http request on some high port
    2. Have the Eero mobile app, when on its own network, request the page via the external IP
    3. Now, if the Eero mobile app can't get a 200 from that http request, hairpin is failing
    4. It could then report the fail to Eero HQ

  • After the recent upgrade to 6.1.0 this is occurring for me. Is this happening to anyone else?

      • SlalomDev
      • SlalomDev
      • 9 mths ago
      • 1
      • Reported - view

      After trying lots of things, I was able to resolve by disabling the HomeKit integration. 

      Like 1
      • lwe
      • lwe
      • 7 mths ago
      • Reported - view

      SlalomDev Wow. Thank you for this tip! This has been driving me nuts and all this time I thought my issue was with My custom DNS server or even my generated Let's Encrypt certs.

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