Bdtyktl

I've made a fresh install of Ubuntu 18.04 LTS months ago, but this week my internet connection via WiFi has suddenly stopped working (tethering works, though: unstably via USB, rather reliably via Bluetooth, which is how I'm currently connecting to this site).

My device is a Dell XPS13 with Qualcomm Atheros: lshw -class network returns

   description: Network controller

   product: QCA6174 802.11ac Wireless Network Adapter

   vendor: Qualcomm Atheros

   physical id: 0

   bus info: pci@0000:3a:00.0

   version: 32

   width: 64 bits

   clock: 33MHz

   capabilities: pm msi pciexpress bus_master cap_list

   configuration: driver=ath10k_pci latency=0

   resources: irq:139 memory:dc000000-dc1fffff

so no logical name; when I check the OS' settings I'm told "No Wi-Fi adapter found - Make sure you have a Wi-Fi adapter plugged and turned on", and indeed when I run ifconfig I get

bnep0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500

    inet 192.168.44.124  netmask 255.255.255.0  broadcast 192.168.44.255

    inet6 fe80::ea16:24ce:ea72:9208  prefixlen 64  scopeid 0x20<link>

    ether 9c:b6:d0:ed:90:24  txqueuelen 1000  (Ethernet)

    RX packets 391  bytes 54441 (54.4 KB)

    RX errors 0  dropped 0  overruns 0  frame 0

    TX packets 644  bytes 97056 (97.0 KB)

    TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0



enp0s20f0u2: flags=4099<UP,BROADCAST,MULTICAST>  mtu 1500

    inet 192.168.42.83  netmask 255.255.255.0  broadcast 192.168.42.255

    inet6 fe80::45ba:d529:b72f:ffc8  prefixlen 64  scopeid 0x20<link>

    ether 66:4d:6f:7e:70:65  txqueuelen 1000  (Ethernet)

    RX packets 62043  bytes 62840918 (62.8 MB)

    RX errors 0  dropped 0  overruns 0  frame 0

    TX packets 49542  bytes 14115031 (14.1 MB)

    TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0



lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536

    inet 127.0.0.1  netmask 255.0.0.0

    inet6 ::1  prefixlen 128  scopeid 0x10<host>

    loop  txqueuelen 1000  (Local Loopback)

    RX packets 23793  bytes 1773826 (1.7 MB)

    RX errors 0  dropped 0  overruns 0  frame 0

    TX packets 23793  bytes 1773826 (1.7 MB)

    TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

Output of lsusb:

Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub

Bus 001 Device 005: ID 0c45:670c Microdia 

Bus 001 Device 004: ID 04f3:20d0 Elan Microelectronics Corp. 

Bus 001 Device 003: ID 0cf3:e300 Atheros Communications, Inc. 

Bus 001 Device 010: ID 2717:ff80  

Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

Any suggestion would be greatly appreciated! No solution found on askubuntu has helped so far - so this is not a duplicate.

UPDATE

This is the outcome of sudo modprobe ath10k_pci && dmesg | grep ath:

[    2.784311] ath10k_pci 0000:3a:00.0: enabling device (0000 -> 0002)

    [    2.786981] ath10k_pci 0000:3a:00.0: pci irq msi oper_irq_mode 2 irq_mode 0 reset_mode 0

[    2.836893] Modules linked in: intel_rapl x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel kvm ath10k_pci(+) snd_hda_codec_realtek(+) dell_laptop(+) snd_soc_skl irqbypass crct10dif_pclmul crc32_pclmul ghash_clmulni_intel snd_hda_codec_generic pcbc snd_soc_skl_ipc ath10k_core snd_hda_ext_core snd_soc_sst_dsp snd_soc_sst_ipc ath snd_soc_acpi snd_soc_core aesni_intel snd_compress mac80211(OE) ac97_bus aes_x86_64 snd_pcm_dmaengine sch_fq_codel crypto_simd glue_helper snd_hda_intel cryptd btusb uvcvideo(+) snd_hda_codec btrtl dell_wmi intel_cstate videobuf2_vmalloc snd_hda_core dell_smbios intel_rapl_perf videobuf2_memops btbcm snd_hwdep btintel videobuf2_v4l2 dcdbas videobuf2_core bluetooth joydev snd_pcm input_leds hid_multitouch videodev wmi_bmof cfg80211(OE) serio_raw dell_wmi_descriptor snd_seq_midi

[    3.077620] ath10k_pci 0000:3a:00.0: Direct firmware load for ath10k/pre-cal-pci-0000:3a:00.0.bin failed with error -2

[    3.077626] ath10k_pci 0000:3a:00.0: Direct firmware load for ath10k/cal-pci-0000:3a:00.0.bin failed with error -2

[    3.078902] ath10k_pci 0000:3a:00.0: qca6174 hw3.2 target 0x05030000 chip_id 0x00340aff sub 1a56:1535

[    3.078903] ath10k_pci 0000:3a:00.0: kconfig debug 0 debugfs 1 tracing 1 dfs 0 testmode 0

[    3.079273] ath10k_pci 0000:3a:00.0: firmware ver WLAN.RM.4.4.1-00079-QCARMSWPZ-1 api 6 features wowlan,ignore-otp crc32 fd869beb

[    3.143217] ath10k_pci 0000:3a:00.0: board_file api 2 bmi_id N/A crc32 20d869c3

[    3.723620] ath10k_pci 0000:3a:00.0: Unknown eventid: 118809

[    3.726696] ath10k_pci 0000:3a:00.0: Unknown eventid: 90118

[    3.727181] ath10k_pci 0000:3a:00.0: htt-ver 3.47 wmi-op 4 htt-op 3 cal otp max-sta 32 raw 0 hwcrypto 1

[    3.813764] ath: EEPROM regdomain: 0x6c

[    3.813765] ath: EEPROM indicates we should expect a direct regpair map

[    3.813765] ath: Country alpha2 being used: 00

[    3.813766] ath: Regpair used: 0x6c

[    3.813798] Modules linked in: nls_iso8859_1 wl(POE) intel_rapl x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel kvm ath10k_pci snd_hda_codec_realtek(+) dell_laptop snd_soc_skl irqbypass crct10dif_pclmul crc32_pclmul ghash_clmulni_intel snd_hda_codec_generic pcbc snd_soc_skl_ipc ath10k_core snd_hda_ext_core snd_soc_sst_dsp snd_soc_sst_ipc ath snd_soc_acpi snd_soc_core aesni_intel snd_compress mac80211(OE) ac97_bus aes_x86_64 snd_pcm_dmaengine sch_fq_codel crypto_simd glue_helper snd_hda_intel cryptd btusb uvcvideo snd_hda_codec btrtl dell_wmi intel_cstate videobuf2_vmalloc snd_hda_core dell_smbios intel_rapl_perf videobuf2_memops btbcm snd_hwdep btintel videobuf2_v4l2 dcdbas videobuf2_core bluetooth joydev snd_pcm input_leds hid_multitouch videodev wmi_bmof cfg80211(OE) serio_raw dell_wmi_descriptor

[    3.813853] Workqueue: ath10k_wq ath10k_core_register_work [ath10k_core]

[    3.813870]  ? ath10k_regd_update+0x2a0/0x2a0 [ath10k_core]

[    3.813872]  ath_regd_init+0x98/0x150 [ath]

[    3.813875]  ath10k_mac_register+0x5e3/0x8e0 [ath10k_core]

[    3.813879]  ath10k_core_register_work+0x651/0x7f0 [ath10k_core]

[    3.813923] Modules linked in: nls_iso8859_1 wl(POE) intel_rapl x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel kvm ath10k_pci snd_hda_codec_realtek(+) dell_laptop snd_soc_skl irqbypass crct10dif_pclmul crc32_pclmul ghash_clmulni_intel snd_hda_codec_generic pcbc snd_soc_skl_ipc ath10k_core snd_hda_ext_core snd_soc_sst_dsp snd_soc_sst_ipc ath snd_soc_acpi snd_soc_core aesni_intel snd_compress mac80211(OE) ac97_bus aes_x86_64 snd_pcm_dmaengine sch_fq_codel crypto_simd glue_helper snd_hda_intel cryptd btusb uvcvideo snd_hda_codec btrtl dell_wmi intel_cstate videobuf2_vmalloc snd_hda_core dell_smbios intel_rapl_perf videobuf2_memops btbcm snd_hwdep btintel videobuf2_v4l2 dcdbas videobuf2_core bluetooth joydev snd_pcm input_leds hid_multitouch videodev wmi_bmof cfg80211(OE) serio_raw dell_wmi_descriptor

[    3.813962] Workqueue: ath10k_wq ath10k_core_register_work [ath10k_core]

[    3.813976]  ? ath10k_regd_update+0x2a0/0x2a0 [ath10k_core]

[    3.813977]  ath_regd_init+0x98/0x150 [ath]

[    3.813980]  ath10k_mac_register+0x5e3/0x8e0 [ath10k_core]

[    3.813984]  ath10k_core_register_work+0x651/0x7f0 [ath10k_core]

[    3.814013] ath10k_pci 0000:3a:00.0: failed to register ieee80211: -22

[    3.814015] ath10k_pci 0000:3a:00.0: could not register to mac80211 (-22)

Code:

sudo apt remove bcmwl-kernel-source && sudo apt install git dkms

git clone -b extended https://github.com/lwfinger/rtlwifi_new.git

sudo dkms add ./rtlwifi_new

sudo dkms install rtlwifi-new/0.6

Reboot.
If you notice weak signal try

sudo modprobe -r rtl8723de && sleep 5 && sudo modprobe rtl8723de ant_sel=1

and see if it is better, if not do

sudo modprobe -r rtl8723de && sleep 5 && sudo modprobe rtl8723de ant_sel=2 

If that doesn't work I can suggest one more thing:
You will have to copy and paste the Wifi - Adapter from another computer or via the internet and install it. I do not know how to do this way, but maybe if you do some research you will find an answer.