Free tools Windows power users keep installed
One-click scans. No signup required.
To pair a Logitech K400r, plug its Logitech Unifying USB receiver directly into a working USB port, turn on the keyboard, and try typing. If it no longer responds, use Logitech Unifying Software to reconnect it: click Next, switch the keyboard off and back on when prompted, type in the test field, then confirm Yes and finish.
Connect the K400r for the first time
- Insert the K400r’s Unifying USB receiver directly into a working USB port on the computer.
- Turn on the computer and the keyboard.
- Try typing. The K400r uses Logitech’s 2.4 GHz Unifying wireless protocol, and its receiver is included with the keyboard package.
The K400r connects through its receiver rather than a Bluetooth pairing menu.
As an Amazon Associate I earn from qualifying purchases.
Reconnect a K400r that has stopped responding
- Check that the batteries are not low. The K400r takes two replaceable AA batteries.
- Connect the receiver directly to the computer, not through a USB hub, KVM switch, or another intermediary.
- Get the latest software available for the K400r from Logitech’s K400r support and Downloads page, then open Logitech Unifying Software.
- Click Next on the welcome screen.
- When prompted, turn the keyboard off and then back on.
- After the keyboard is detected, type a test message in the test field. If it works, click Yes, then Next and Finish. If it does not, repeat the keyboard off/on step.
If reconnection still fails after a couple of attempts, Logitech recommends restarting the computer and trying again. Logitech’s K400r troubleshooting page continues to describe Unifying Software, while noting that the software is no longer supported or maintained. It recommends Logi Options+ for supported devices, but does not establish that Options+ can pair the K400r; check Logitech’s current K400r support page for software availability and compatibility.
Fix repeated dropouts
If the keyboard connects but keeps disconnecting, check the physical connection and radio environment before replacing hardware:
#1 Best Overall
- Media-Friendly: The K400 Plus wireless touch TV keyboard gives you integrated, comfortable control of your PC-to-TV entertainment, eliminating the clutter of a separate keyboard and mouse
- Plug-and-Play: Simply plug the Unifying receiver into a USB port and the wireless touchpad keyboard is ready to go; adjust controls using the Logitech Options Software to save preferred settings
- Power-Packed: Built with laid-back control in mind, this wireless TV keyboard has a reliable and long battery life of up to 18 months (2), including an on/off button to help it go even longer
- Wireless Freedom: Designed for seamless comfort and control, this HTPC keyboard boasts a range of up to 33 ft (1) wireless connectivity, with quiet keys and a large touchpad for easy navigation
- Broad Compatibility: Designed for use with Windows 7, Windows 8, Windows 10 and later, Android 7 or later, and Chrome OS
- Try a different USB port, keeping the receiver directly connected to the computer.
- Move the keyboard closer to the receiver. Logitech lists a wireless range of up to 10 meters (33 feet) in the K400r specifications; actual usable distance can vary with placement and interference.
- Keep other electrical devices at least 8 inches (20 cm) from the receiver.
- Replace the batteries if their charge may be low.
- Where practical, move the receiver away from metal surfaces and sources of radio-frequency interference.
Use a replacement receiver only if it is Unifying
If the original receiver is missing or damaged, a replacement can work only if it is a Logitech Unifying receiver. Check for the Unifying logo and the receiver’s specific marking; a generic 2.4 GHz receiver or a Logi Bolt receiver is not interchangeable just because it is made by Logitech or uses USB.
Logitech says a Unifying-ready device can be paired with any Unifying receiver, and one receiver can be paired with up to six Unifying devices at a time. The K400r’s specifications identify it as a Unifying device. For a replacement, verify the Unifying marking and compatibility, and consider the seller’s reliability and return terms.
Quick Recap
Best Value
- Logitech MK470 cordless combo features a compact modern designed keyboard with low-profile scissor keys, a number pad and a layout optimized for Windows
- This wireless keyboard and mouse set also features a comfortable, ambidextrous 3 button mouse with high precision optical tracking and mechanical scroll wheel, Sensor resolution: 1000 DPI
- Whisper quiet keyboard and lab-tested, noise-reduced mouse means an ultra quiet work experience for you and those around you both in the office and at home
- Simple plug-and-play USB nano receiver offers a strong reliable 2.4 GHz wireless connection with 10 m (33ft) of range(1) (1) Wireless range may vary based on environmental and computing conditions
- Auto-sleep feature saves battery life, allowing for 36 months of keyboard use and 18 months of mouse use(2) (2) Battery life may vary based on user and computing conditions
Rank #4
- Modern Design: The slim wireless keyboard profile and modern minimalist design transform and elevate your desk setup into a visual statement
- Pair Devices: Easy Switch lets you pair and quickly alternate between multiple electronic devices, so you can type on your computer and your smartphone or tablet seamlessly
- Numeric Keypad: Enjoy a fluid, laptop-like comfortable typing experience that’s whisper-quiet; number pad and 12 FN keys are available for easy access and media shortcuts
- Extended Autonomy: Benefit from long battery life (1) with auto-sleep feature — plus a strong, secure wireless range up to 10m (2) via Bluetooth or the included 2.4GHz USB receiver
- For Multi-OS: Use across multiple devices and platforms - Windows on laptops and PC via the USB A receiver or BT; tablets, phones, macOS, iOS, iPadOS, Android, Chrome and Linux via Bluetooth
Rank #3
- Type on Any Device: A new type of wireless computer keyboard for your desk that also works with your tablet and smartphone; connect with any Bluetooth-enabled device with external keyboard support. Wireless range: > 10m wireless range
- Easy-Switch Dial: Simply turn the dial of the Logitech K480 keyboard to switch typing between 3 connected Bluetooth wireless devices, you can work with Windows, macOS, Chrome OS, Android, and iPadOS
- Familiar Keyboard Layout: Find all the shortcut keys you use the most, but in a space-saving design that lets you place your mouse close to you, for less arm reaching and better posture
- Integrated Cradle: A cradle to hold your phone or tablet at just the right angle for you to read while you type; fits most phones and tablets up to 0.4 inches thick and 10 inches wide
- Reliable Power: This portable, wireless Bluetooth keyboard comes with 2 pre-installed AAA batteries which can last up to 24 months (2) and is compatible with wired, wireless or Bluetooth mice. Battery indicator light
Rank #2
- Long-range wireless: Control your TV-connected laptop from the couch with 33 feet/10 meter wireless range (Wireless range may vary due to environmental and computing conditions.)
- Built-in multi-touch touchpad: Large (3.5-inch) touchpad with multi-touch navigation for easier web browsing
- Plug-and-play setup: Plug the tiny Logitech Unifying wireless receiver into your laptop and start surfing the web
- Sleek, low-profile keys: Easy and comfortable typing on quiet keys with bold, easy-to-read characters
- For Windows-based laptops: Works with Windows 7, Windows Vista and Windows XP
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
