What's great
The Antminer S21 is powerful, efficient, and stable once set up. It delivers consistent hashrate, keeps safe temperatures, and runs quietly enough for its performance level. It's great for SHA-256 mining and perfect for long-term Bitcoin holders.
What needs improvement
Initial setup could be smoother-firmware updates and syncing take time, and the interface could refresh faster to show hashrates accurately during first use.
vs Alternatives
The S21 would not hash at first even though the fans worked, so I did a restart, swapped the Ethernet cable, and checked all the pool logins, and I chose this miner since it runs SHA-256 for Bitcoin which gives me the liquidity I want, and after reseating power leads, updating to the latest firmware, and factory resetting then re-applying pool and wallet, it came onine 42 hours after payment, stayed near 65 dB at one meter, kept temps sready