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To pair a Logitech K400r, plug its Logitech Unifying USB receiver directly into your computer, switch on the keyboard, and try typing. If it does not connect, use Logitech Unifying Software to reconnect it: choose 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
- Plug the K400r’s Unifying receiver directly into a working USB port on the computer—not a hub or KVM switch.
- Turn on the computer and the keyboard.
- Try typing. The receiver is included with the K400r package, according to Logitech’s technical specifications.
The K400r uses Logitech’s 2.4 GHz Unifying wireless connection, not Bluetooth. Its listed wireless range is up to 10 meters (33 feet); actual performance can depend on receiver placement and interference. Logitech K400r specifications
Reconnect the keyboard with Logitech Unifying Software
- Check that the batteries are working and the receiver is plugged directly into the computer.
- Get the available software from the K400r support and downloads page, then open Logitech Unifying Software.
- Select Next on the welcome screen.
- When prompted, switch the keyboard off and then back on.
- After the keyboard is detected, type a test message. If it works, select Yes, then Next and Finish. If it does not, repeat the off/on step.
These steps follow Logitech’s general Unifying connection guide and its K400r troubleshooting instructions. If reconnection still fails after a couple of attempts, Logitech recommends restarting the computer and trying again.
Use a replacement receiver only if it is Unifying-compatible
If the original receiver is missing or damaged, look for a Logitech Unifying receiver and verify the Unifying logo and receiver marking. Logitech says a Unifying-ready device can pair with any Unifying receiver; a receiver can support up to six Unifying devices at a time. The K400r is identified as a Unifying device in its specifications. See Logitech’s receiver connection guidance and receiver compatibility information.
#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
Do not assume that a Logi Bolt receiver or a generic 2.4 GHz USB receiver will work: those are different receiver types, not interchangeable labels for Unifying. Logitech explains the distinctions in its receiver guidance.
Fix a K400r that keeps disconnecting
- Replace weak batteries. The K400r uses two replaceable AA batteries, and Logitech lists low battery as a possible cause. K400r specifications
- Change the USB connection. Plug the receiver directly into another working computer USB port; avoid hubs and KVM switches.
- Improve receiver placement. Move the keyboard closer and keep other electrical devices at least 8 inches (20 cm) from the receiver.
- Reduce interference. Where practical, avoid placing the receiver near metal surfaces or sources of radio-frequency interference.
These checks come from Logitech’s K400r troubleshooting guidance. If the keyboard still will not reconnect, restart the computer and repeat the software pairing steps.
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
Software availability for this older model
Logitech’s K400r troubleshooting guidance still describes reconnection with Logitech Unifying Software, while noting that the software is no longer supported or maintained and recommending Logi Options+ for supported devices. Logitech’s available information does not confirm that Logi Options+ can pair the K400r. Check the current K400r support and downloads page for software availability and model compatibility rather than assuming the newer app supports it.
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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
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