If you are running Ubuntu, Fedora, or Debian, the kernel likely includes a staging driver, but it's often broken. For AC1200 adapters, you need to install via dkms from GitHub repos (e.g., morrownr/88x2bu-20210702 for RTL8812BU). Avoid the default rtl88x2bu-dkms from Ubuntu repos—it is typically outdated.
For newer kernels (Linux 5.5 and later), certain MediaTek MT7612U‑based adapters may work out of the box with the built‑in mt76 driver. To check: wifi 5 ac1200mbps wireless usb adapter driver
A USB 3.0 adapter has the potential to deliver higher and more stable throughput because the USB 3.0 interface (up to 5 Gbps) is far faster than the maximum Wi‑Fi speed of the adapter (1.2 Gbps). A USB 2.0 adapter (480 Mbps max interface speed) can become a bottleneck, especially on the 5 GHz band. If you are running Ubuntu, Fedora, or Debian,
Follow the on-screen prompts and restart your computer when prompted. Plug the AC1200 USB adapter into a working USB port. For newer kernels (Linux 5
This is a very common error for USB WiFi adapters. It usually means there is a conflict with a previously installed driver.