我已经使用安装了 Ubuntu 18.04 的联想 Yoga 500 笔记本电脑一年多了，由于某些未知原因，我最近开始遇到 WiFi 连接问题。这可能与某些内核升级有关，但我不能保证一定是这样，因为我通常使用有线连接，并没有立即意识到这个问题。
问题是，所有 wifi 信号（来自不同的无线网络）都被发现非常弱。为了连接，甚至为了检测它们，我需要将笔记本电脑放在靠近路由器的地方。当我在同一台笔记本电脑上使用 Windows 时，我没有遇到此问题。
uname -r 的输出：
4.15.0-46-generic
lshw 类网络的输出：
*-network
description: Wireless interface
product: Dual Band Wireless-AC 3165 Plus Bluetooth
vendor: Intel Corporation
physical id: 0
bus info: pci@0000:02:00.0
logical name: wlp2s0
version: 99
serial: 08:d4:0c:d4:49:50
width: 64 bits
clock: 33MHz
capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless
configuration: broadcast=yes driver=iwlwifi driverversion=4.15.0-46-generic firmware=29.1044073957.0 latency=0 link=no multicast=yes wireless=IEEE 802.11
resources: irq:128 memory:d2200000-d2201fff
*-network
description: Ethernet interface
product: RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller
vendor: Realtek Semiconductor Co., Ltd.
physical id: 0
bus info: pci@0000:03:00.0
logical name: enp3s0
version: 15
serial: 54:ee:75:93:e1:97
size: 100Mbit/s
capacity: 1Gbit/s
width: 64 bits
clock: 33MHz
capabilities: pm msi pciexpress msix bus_master cap_list ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd 1000bt 1000bt-fd autonegotiation
configuration: autonegotiation=on broadcast=yes driver=r8169 driverversion=2.3LK-NAPI duplex=full firmware=rtl8168h-2_0.0.2 02/26/15 ip=147.156.160.216 latency=0 link=yes multicast=yes port=MII speed=100Mbit/s
resources: irq:17 ioport:c000(size=256) memory:d2104000-d2104fff memory:d2100000-d2103fff
lspci 的输出：
00:00.0 Host bridge: Intel Corporation Xeon E3-1200 v5/E3-1500 v5/6th Gen Core Processor Host Bridge/DRAM Registers (rev 08)
00:02.0 VGA compatible controller: Intel Corporation Skylake GT2 [HD Graphics 520] (rev 07)
00:14.0 USB controller: Intel Corporation Sunrise Point-LP USB 3.0 xHCI Controller (rev 21)
00:14.2 Signal processing controller: Intel Corporation Sunrise Point-LP Thermal subsystem (rev 21)
00:15.0 Signal processing controller: Intel Corporation Sunrise Point-LP Serial IO I2C Controller #0 (rev 21)
00:16.0 Communication controller: Intel Corporation Sunrise Point-LP CSME HECI #1 (rev 21)
00:17.0 SATA controller: Intel Corporation Sunrise Point-LP SATA Controller [AHCI mode] (rev 21)
00:1c.0 PCI bridge: Intel Corporation Sunrise Point-LP PCI Express Root Port #1 (rev f1)
00:1c.4 PCI bridge: Intel Corporation Sunrise Point-LP PCI Express Root Port #5 (rev f1)
00:1c.5 PCI bridge: Intel Corporation Sunrise Point-LP PCI Express Root Port #6 (rev f1)
00:1f.0 ISA bridge: Intel Corporation Sunrise Point-LP LPC Controller (rev 21)
00:1f.2 Memory controller: Intel Corporation Sunrise Point-LP PMC (rev 21)
00:1f.3 Audio device: Intel Corporation Sunrise Point-LP HD Audio (rev 21)
00:1f.4 SMBus: Intel Corporation Sunrise Point-LP SMBus (rev 21)
01:00.0 3D controller: NVIDIA Corporation GK208BM [GeForce 920M] (rev a1)
02:00.0 Network controller: Intel Corporation Dual Band Wireless-AC 3165 Plus Bluetooth (rev 99)
03:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 15)
rfkill list all 的输出：
0: ideapad_wlan: Wireless LAN
Soft blocked: no
Hard blocked: no
1: ideapad_bluetooth: Bluetooth
Soft blocked: no
Hard blocked: no
2: phy0: Wireless LAN
Soft blocked: no
Hard blocked: no
3: hci0: Bluetooth
Soft blocked: no
Hard blocked: no
我尝试安装英特尔的固件（从https://www.intel.com/content/www/us/en/support/articles/000005511/network-and-io/wireless-networking.html)，但在将文件复制到 /lib/firmware 后，我发现没有任何区别。事实上，我认为我做得不对，因为我仍然运行着我之前的固件版本，正如我从 dmesg | grep -i firmware 的输出中理解的那样：
[ 0.028000] Spectre V2 : Enabling Restricted Speculation for firmware calls
[ 0.088498] ACPI: [Firmware Bug]: BIOS _OSI(Linux) query ignored
[ 2.323888] [drm] Finished loading DMC firmware i915/skl_dmc_ver1_26.bin (v1.26)
[ 23.557242] iwlwifi 0000:02:00.0: loaded firmware version 29.1044073957.0 op_mode iwlmvm
[ 24.301855] Bluetooth: hci0: Intel Bluetooth firmware file: intel/ibt-hw-37.8.10-fw-1.10.3.11.e.bseq
[ 24.596957] Bluetooth: hci0: Intel firmware patch completed and activated
我下载的是版本 14，而不是 29。我不知道这是否相关，但以防万一还是想提一下。
我还应该指出，我的一个同事有一台一模一样的笔记本电脑，也是 Ubuntu 18.04，使用相同的无线控制器和 Linux 内核。但是，他没有遇到我的问题。
如果您需要更多信息，请告诉我。提前谢谢您。
编辑：我将内核更新为 4.15.0-47-generic，问题仍然存在。我还将我的所有命令输出与同事的命令输出进行了比较，它们完全相同（当然，除了他的例子中的“link = yes”）。我即将将 Ubuntu 版本升级到 18.10，看看是否能解决问题，但我不太乐观……
编辑2：我确认升级到 Ubuntu 18.10 没有帮助。