Amplifi and Pixel 3xl problems

  • Can't figure out exactly why it's this specific configuration, but me and another user with the same setup are having the exact same issues. Poor wifi performance when using a Pixel 3xl phone connected to an Amplifi. Upload speeds are around 3up through the amplifi (normally 20ish), and it has issues uploading pictures or downloading certain webpages.

    • Other devices work fine on the Amplifi and can bring everything up, speeds are good

    • Using a different router on the same network with the same configuration work fine with the Pixel, everything comes up, speeds are good

    • Using a 3rd party VPN works fine, everything comes up, speeds are good

    • Phone, router, and phone network settings have all been reset

    Has anyone else experienced similar problems?

  • I have a Pixel 3XL and hasn't experienced any issues.

  • Thanks for posting your experience. What do you get on a speedtest over wifi on your Pixel 3XL?

  • Speed test examples:
    Running on
    Over wifi:
    Ping - 35ms
    Jitter - 47ms
    Download - 46.9Mbps
    Upload - 0.4Mbps

    Over wifi through a 3rd party VPN:
    Ping - 37ms
    Jitter - 23ms
    Download - 45.9Mbps
    Upload - 11.6Mbps

    Can't attribute this to ISP throttling though, because switching routers also allows full speed. It's only through the Amplifi that the issue occurs.

  • We've made some progress contacting Ubiquiti about this. We found that when the ISP disabled MSS clamping, it got better.
    Ubiquiti gave us this info:

    Yes, we use MSS clamping. But we found that some PPPoE servers set incorrect MTU value themselves. In other words, Amplifi is told by the PPPoE server to use larger MTU than the server can really handle. Besides MSS clamping, we send ICMP "fragmentation needed" message back to the client when it sends a too big packet (for example, VPN UDP encrypted packet - MSS clamping does not apply to these). End-to-end VPN over PPPoE may fail for this reason - if the client has default MTU 1500 and ignores these ICMP messages. It was possible that Pixel was sending non-TCP packets and ignored"fragmentation needed" ICMP messages for some reason.

    The developers will be testing Pixel on a PPPoE setup and try to determine the if ICMP messages were ignored. This will take some time and can't give an ETA right now. But will reach out to you soon with an update on testings.

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