[5Z ZS620KL] Slow Wifi speed after july update

cAmiatcAmiat Level 1
edited September 2020 in ZenFone 5 Series

My phone has been getting slow wifi speeds after the update. Connecting to internet times out and watching videos will also fail partway.

I tried downgrading by downloading the previous OTA update and sideloading it with ADB, but the device aborts with error code 1 (can't downgrade to update older than installed update).

Is there a way for me to downgrade an update?

I tried resetting network settings, but it's still the same results. Other devices on the same network habe no issues with connections, so it's definitely not a problem with the internet, but with the phone.


  • Start adb with root permission on your PC. Install the firmware and wait.

  • cAmiatcAmiat Level 1

    Adb sideload doesn't need root. It's the device that doesn't allow downgrading firmware. I'm wondering if there's a fix for the downgrade issue.

  • Downgrade to Pie then upgrade to the desired version.

  • I've had WiFi problems on Pie, low signal strength when in landscape or with the hands over the antennae.

  • Hi friends,

    Thank you all for your asking.


    Please perform Android Q downgrade to P (2019/12/26) first, then auto upgrade one by one till the Android P version you like.

    #ZS620KL Firmware Spot


    >WiFi Issue

    Try to enter "Safe Mode" first. If wifi works well in "Safe Mode", please check on any disturbance from the installed 3rd party Apps

    #How to enter and exit "Safe Mode"


    2. For "doing network reset", do you mean "Network settings reset" on phone or on the router?

    3. Check SMMI test

    Calculator> type ".12345+=">SMMI TEST>Single Test>WiFi Test

  • cAmiatcAmiat Level 1
    edited June 2020

    I tried downgrading to android P via adb sideload, but the error still persists

    Update package is older than the current build, expected a build newer than timestamp 1589945520 but package has timestamp 1570516830 and downgrade not allowed.
    Instsall from ADB completed with status 1.
    Installation aborted.

    Okay, I downloaded the downgrade package and was then able to downgrade when I transferred it to the sdcard. On the other hand, the only complaint I have is that the downgrade reset my phone and I wasn't able to make backups and lost everything >:(

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