Antminer S21, S21 Pro & T21 Firmware – VNISH Overclocking & Undervolt

VNISH Firmware 1.3.6 for Antminer S21, S21 Pro & T21 — Download, Install & Update

There is no hotel fee in version 1.3.6

We can add your personal Dev fee and proxying your Fee to any pool, similar to hotel fee option.

Build firmware for free

TO UPDATE TO THE LATEST VERSION YOU CAN USE VNISH MONITORING TOOL. THE UTILITY SCANS YOUR NETWORK, DETERMINES THE MINER MODEL AND INSTALLATION TYPE, AND AUTOMATICALLY UPDATES YOUR VNISH FIRMWARE TO THE LATEST VERSION.

INSTALLING VNISH FIRMWARE FOR ANTMINER S21, S21 PRO & T21:

Download the VNISH firmware for your Antminer S21, S21 Pro or T21 from the “NAND Download Install” section for your miner model and control board.
Installation is only possible using the HASHCORE TOOLKIT utility. Download the utility and carefully read the installation instructions.

If you don’t know which control board is installed on your miner:

We recommend downloading the HASHCORE TOOLKIT (Windows) + firmware bundle.
The utility will automatically detect your Antminer model and control board type, then install the VNISH firmware correctly and safely.

Specifics for the CVitek board:

After rebooting a miner with a CVitek board, the stock firmware may revert.
To restore the VNISH firmware:
Scan the network with the HASHCORE TOOLKIT, or
Use phoenix-scanner in the background – the VNISH firmware will be restored automatically.

This guide helps you download, install and update VNISH firmware for Antminer S21, S21 Pro and T21 while minimizing the risk of installation failures and improving miner stability.

⚠️ATTENTION: Check the stock firmware date. Firmware can be installed using the Toolkit 1.7.4 or newer on stock firmware with any date.

If you have BITMAIN firmware installed from 2024 year that cant be flashed to vnish and you see the ssh error, you can update the firmware using the stock web update file on a newer date. If you cannot find the stock update file for your model, you will need to downgrade the firmware using an SD image.

Amlogic (a113d) control boards with firmware from september 2025 and newer cant be downgrade using sd image.
Instructions for unlocking AML control boards to install VNISH firmware:
➡️ UNLOCK-AML

Resources and Utilities

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Firmware Vnish for Bitmain
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