我尝试在 Kubuntu 18.04 下使用蓝牙让耳机工作。几分钟后，它们确实工作了，但后来我不小心更改了某些东西，从那以后我就无法让它们工作了。它们短暂工作这一事实非常重要，因为这表明硬件没有问题，并且安装了所有必要的软件。
在解决这个问题的过程中，我无意中引入了另一个问题：以前显示在窗口中的笔记本电脑blueman不再显示，因此，除非我再次让笔记本电脑可见，否则无法将笔记本电脑与耳机配对。
我不知道我是怎么搞砸的，但事实上，在我扰乱配置之前，配置一直有效，这排除了造成困难的几个原因。硬件没有问题；所有必要的模块都已安装并正在运行，各种配置文件都井然有序。我认为只需进行一点小调整即可解决问题，但如果我能找到它，那就太糟糕了。调整配置文件有一个很大的危险：我可能会让问题变得更糟。
耳机工作时处于低保真模式，所以这是需要修复的另一个问题。但那可以以后再解决。
根据 pilot6 的建议，我提供了更多输出：
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$ lspci -knn | grep Net -A3; lsusb; dmesg | grep -i blue
03:00.0 Network controller [0280]: Intel Corporation Dual Band Wireless-AC 3168NGW [Stone Peak] [8086:24fb] (rev 10)
Subsystem: Intel Corporation Device [8086:2110]
Kernel driver in use: iwlwifi
Kernel modules: iwlwifi
Bus 001 Device 004: ID 8087:0aa7 Intel Corp.
Bus 001 Device 003: ID 04f2:b5d6 Chicony Electronics Co., Ltd
Bus 001 Device 002: ID 0438:7900 Advanced Micro Devices, Inc.
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 003 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 002 Device 002: ID 046d:c534 Logitech, Inc. Unifying Receiver
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
[ 23.561079] Bluetooth: Core ver 2.22
[ 23.561116] Bluetooth: HCI device and connection manager initialized
[ 23.561122] Bluetooth: HCI socket layer initialized
[ 23.561125] Bluetooth: L2CAP socket layer initialized
[ 23.561130] Bluetooth: SCO socket layer initialized
[ 23.925362] Bluetooth: hci0: read Intel version: 370810225019140f36
[ 23.925364] Bluetooth: hci0: Intel device is already patched. patch num: 36
[ 39.347022] Bluetooth: BNEP (Ethernet Emulation) ver 1.3
[ 39.347024] Bluetooth: BNEP filters: protocol multicast
[ 39.347030] Bluetooth: BNEP socket layer initialized
[ 149.908763] Bluetooth: RFCOMM TTY layer initialized
[ 149.908775] Bluetooth: RFCOMM socket layer initialized
[ 149.908787] Bluetooth: RFCOMM ver 1.11
[ 1275.443468] Bluetooth: hci0: Ignoring error of Inquiry Cancel command
[54838.153358] Bluetooth: hci0: SCO packet for unknown connection handle 0
[54838.153364] Bluetooth: hci0: SCO packet for unknown connection handle 0
[54838.153366] Bluetooth: hci0: SCO packet for unknown connection handle 0
[54838.153368] Bluetooth: hci0: SCO packet for unknown connection handle 0
[54838.163482] Bluetooth: hci0: SCO packet for unknown connection handle 0
[64916.775086] Bluetooth: hci0: urb 00000000713b37a0 failed to resubmit (2)
[64973.785644] Bluetooth: hci0: read Intel version: 370810225019140f36
[64973.785648] Bluetooth: hci0: Intel device is already patched. patch num: 36
[64973.841857] Bluetooth: hci0: hardware error 0x0c