VMG3312-T20A: Cannot upgrade firmware

JM24

Hello,

I had the VMG3312-T20A with the original firmware from T-Mobile. I encountered some issues, so I downloaded the latest firmware available on the Zyxel site and upgraded the modem to V5.30(ABFX.5)C0. The upgrade went smoothly, and everything is functioning properly.

However, my service provider increased the connection speeds, and now my modem seems to be running slow. T-Mobile's remote diagnostics detected that I am using outdated firmware and prompted me to upgrade to the firmware they provided, VMG3312-T20A_V530ABIV2b6_D0.bin. The problem is, I'm unable to upgrade to this firmware. Whenever I try, it throws an error and reboots itself.

My suspicion is that I originally had custom T-Mobile firmware, and when I upgraded, I overwrote it with generic firmware, making it impossible to revert.

Do you have any suggestions or ideas on how I can address this issue?

Thank you.

JM24

Is there, like, a super easy way to totally reset the router and bring back the original firmware? Can you, I don't know, trick it into uploading the firmware without caring about the built-in checks? Seriously, any fix for this mess?

Or are we stuck with a modem that's pretty much a goner because T-Mobile's pointing fingers at the stock firmware for making the internet crawl like a snail? Ugh.