@6x12
Thanks for the tip! Since iwconfig isn’t on my system, rather than installing it I went with the alternative command in the second link you posted
Before I tried those solutions, I wanted to know the current setting from what I was changing:
❯ iw dev wlp3s0 info | grep txpower
txpower 31.00 dBm
Okay, so 31 dBm, but really that’s the setting that “auto” decided on. If I revert, I think I should revert to txpower auto, probably.
The person in the first link experimented that 20 dBm seemed to work well before things became unstable again… so I’ll try that:
❯ sudo iw dev wlp3s0 set txpower fixed 2000
❯ iw dev wlp3s0 info | grep txpower
txpower 20.00 dBm
It didn’t work… I turn off the wifi, turn it on again, my network appears, and connecting to it presents “Incorrect password” and a prompt to type it in again. I can repeat, but if I press cancel, we get the “Secrets were required, but not provided.” message.
Perhaps I failed to notice this before, but at least it means the authentication is failing. So that might narrow down the troubleshooting.
Anyway, just to be sure, I tried again at the even lower power of 10 dBm:
❯ sudo iw dev wlp3s0 set txpower fixed 1000
❯ iw dev wlp3s0 info | grep txpower
txpower 10.00 dBm
Which also didn’t work.
Ultimately, I’m reassured slightly, because if this did fix the problem I would have been very confused why the LiveUSB doesn’t need it whilst my on-device installation does 
Oh geeze! Thank you for paying attention. I didn’t realise my journalctl was cached back to May! I thought it was on the RAM caching from when I last turned it on, doh!
I thought the times were out! Please completely ignore that post, I might edit it out since it’s misleading.
Here’s the new log, where I suspect these filtered results should provide some clues (especially the last block):
> journalctl --since="27 hours ago"
...
Jun 09 09:00:51 Manjaro-Laptop kernel: brcmfmac: brcmf_fw_alloc_request: using brcm/brcmfmac43602-pcie for chip BCM43602/2
Jun 09 09:00:51 Manjaro-Laptop kernel: brcmfmac 0000:03:00.0: Direct firmware load for brcm/brcmfmac43602-pcie.Apple Inc.-MacBookPro14,3.bin failed with error -2
Jun 09 09:00:51 Manjaro-Laptop kernel: brcmfmac 0000:03:00.0: Direct firmware load for brcm/brcmfmac43602-pcie.clm_blob failed with error -2
Jun 09 09:00:51 Manjaro-Laptop kernel: brcmfmac 0000:03:00.0: Direct firmware load for brcm/brcmfmac43602-pcie.txcap_blob failed with error -2
Jun 09 09:00:51 Manjaro-Laptop kernel: vga_switcheroo: enabled
Jun 09 09:00:51 Manjaro-Laptop systemd-timesyncd[418]: Network configuration changed, trying to establish connection.
Jun 09 09:00:51 Manjaro-Laptop systemd-timesyncd[418]: Network configuration changed, trying to establish connection.
Jun 09 09:00:51 Manjaro-Laptop systemd-timesyncd[418]: Network configuration changed, trying to establish connection.
Jun 09 09:00:51 Manjaro-Laptop systemd[1]: Finished Create System Files and Directories.
Jun 09 09:00:51 Manjaro-Laptop systemd[1]: Rebuild Dynamic Linker Cache skipped, no trigger condition checks were met.
Jun 09 09:00:51 Manjaro-Laptop systemd[1]: Initial Setup skipped, unmet condition check ConditionFirstBoot=yes
Jun 09 09:00:51 Manjaro-Laptop systemd[1]: First Boot Complete skipped, unmet condition check ConditionFirstBoot=yes
Jun 09 09:00:51 Manjaro-Laptop systemd[1]: Rebuild Journal Catalog skipped, unmet condition check ConditionNeedsUpdate=/var
Jun 09 09:00:51 Manjaro-Laptop systemd[1]: Save Transient machine-id to Disk skipped, unmet condition check ConditionPathIsMountPoint=/etc/machine-id
Jun 09 09:00:51 Manjaro-Laptop systemd[1]: Update is Completed skipped, no trigger condition checks were met.
Jun 09 09:00:51 Manjaro-Laptop systemd[1]: Starting Record System Boot/Shutdown in UTMP...
Jun 09 09:00:51 Manjaro-Laptop kernel: intel_tcc_cooling: Programmable TCC Offset detected
Jun 09 09:00:51 Manjaro-Laptop systemd[1]: Finished Record System Boot/Shutdown in UTMP.
Jun 09 09:00:51 Manjaro-Laptop kernel: intel_pmc_core intel_pmc_core.0: initialized
Jun 09 09:00:51 Manjaro-Laptop kernel: intel_rapl_common: Found RAPL domain package
Jun 09 09:00:51 Manjaro-Laptop kernel: intel_rapl_common: Found RAPL domain core
Jun 09 09:00:51 Manjaro-Laptop kernel: intel_rapl_common: Found RAPL domain uncore
Jun 09 09:00:51 Manjaro-Laptop kernel: intel_rapl_common: Found RAPL domain dram
Jun 09 09:00:51 Manjaro-Laptop kernel: brcmfmac: brcmf_c_process_clm_blob: no clm_blob available (err=-2), device may have limited channels available
Jun 09 09:00:51 Manjaro-Laptop kernel: brcmfmac: brcmf_c_process_txcap_blob: no txcap_blob available (err=-2)
Jun 09 09:00:51 Manjaro-Laptop kernel: brcmfmac: brcmf_c_preinit_dcmds: Firmware: BCM43602/2 wl0: Nov 10 2015 06:38:10 version 7.35.177.61 (r598657) FWID 01-ea662a8c
Jun 09 09:00:51 Manjaro-Laptop kernel: i915 0000:00:02.0: [drm] Cannot find any crtc or sizes
Jun 09 09:00:51 Manjaro-Laptop kernel: brcmfmac 0000:03:00.0 wlp3s0: renamed from wlan0
...
Jun 09 09:01:02 Manjaro-Laptop wpa_supplicant[640]: wlp3s0: Removed BSSID 52:41:b9:0a:72:d3 from ignore list (clear)
Jun 09 09:01:02 Manjaro-Laptop wpa_supplicant[640]: wlp3s0: Trying to associate with SSID 'FiveGHz'
Jun 09 09:01:02 Manjaro-Laptop systemd[1]: NetworkManager-dispatcher.service: Deactivated successfully.
Jun 09 09:01:02 Manjaro-Laptop NetworkManager[555]: <info> [1780963262.2141] device (wlp3s0): supplicant interface state: scanning -> associating
Jun 09 09:01:02 Manjaro-Laptop NetworkManager[555]: <info> [1780963262.2147] device (p2p-dev-wlp3s0): supplicant management interface state: scanning -> associating
...
Jun 09 09:01:02 Manjaro-Laptop wpa_supplicant[640]: wlp3s0: CTRL-EVENT-ASSOC-REJECT bssid=00:00:00:00:00:00 status_code=16
Jun 09 09:01:02 Manjaro-Laptop wpa_supplicant[640]: wlp3s0: Added BSSID 52:41:b9:0a:72:d3 into ignore list, ignoring for 10 seconds
Jun 09 09:01:02 Manjaro-Laptop NetworkManager[555]: <info> [1780963262.3247] device (wlp3s0): supplicant interface state: associating -> disconnected
Jun 09 09:01:02 Manjaro-Laptop NetworkManager[555]: <info> [1780963262.3248] device (p2p-dev-wlp3s0): supplicant management interface state: associating -> disconnected
...
Jun 09 09:00:58 Manjaro-Laptop NetworkManager[555]: <info> [1780963258.7211] policy: auto-activating connection 'FiveGHz' (41a87b96-7d83-4bac-a22e-89c12f84f2fe)
Jun 09 09:00:58 Manjaro-Laptop NetworkManager[555]: <info> [1780963258.7216] device (wlp3s0): Activation: starting connection 'FiveGHz' (41a87b96-7d83-4bac-a22e-89c12f84f2fe)
Jun 09 09:00:58 Manjaro-Laptop NetworkManager[555]: <info> [1780963258.7218] device (wlp3s0): state change: disconnected -> prepare (reason 'none', managed-type: 'full')
Jun 09 09:00:58 Manjaro-Laptop NetworkManager[555]: <info> [1780963258.7220] manager: NetworkManager state is now CONNECTING
Jun 09 09:00:59 Manjaro-Laptop NetworkManager[555]: <info> [1780963259.2320] device (wlp3s0): set-hw-addr: reset MAC address to 8C:85:90:32:7F:DC (preserve)
Jun 09 09:00:59 Manjaro-Laptop NetworkManager[555]: <info> [1780963259.2356] device (wlp3s0): state change: prepare -> config (reason 'none', managed-type: 'full')
Jun 09 09:00:59 Manjaro-Laptop NetworkManager[555]: <info> [1780963259.2358] device (wlp3s0): Activation: (wifi) access point 'FiveGHz' has security, but secrets are required.
Jun 09 09:00:59 Manjaro-Laptop NetworkManager[555]: <info> [1780963259.2358] device (wlp3s0): state change: config -> need-auth (reason 'none', managed-type: 'full')
Jun 09 09:00:59 Manjaro-Laptop NetworkManager[555]: <info> [1780963259.2365] device (wlp3s0): state change: need-auth -> prepare (reason 'none', managed-type: 'full')
Jun 09 09:00:59 Manjaro-Laptop NetworkManager[555]: <info> [1780963259.2366] device (wlp3s0): state change: prepare -> config (reason 'none', managed-type: 'full')
Jun 09 09:00:59 Manjaro-Laptop NetworkManager[555]: <info> [1780963259.2367] device (wlp3s0): Activation: (wifi) connection 'FiveGHz' has security, and secrets exist. No new secrets needed.
Jun 09 09:00:59 Manjaro-Laptop NetworkManager[555]: <info> [1780963259.2367] Config: added 'ssid' value 'FiveGHz'
Jun 09 09:00:59 Manjaro-Laptop NetworkManager[555]: <info> [1780963259.2367] Config: added 'scan_ssid' value '1'
Jun 09 09:00:59 Manjaro-Laptop NetworkManager[555]: <info> [1780963259.2367] Config: added 'bgscan' value 'simple:30:-70:86400'
Jun 09 09:00:59 Manjaro-Laptop NetworkManager[555]: <info> [1780963259.2368] Config: added 'key_mgmt' value 'WPA-PSK WPA-PSK-SHA256 FT-PSK'
Jun 09 09:00:59 Manjaro-Laptop NetworkManager[555]: <info> [1780963259.2368] Config: added 'auth_alg' value 'OPEN'
Jun 09 09:00:59 Manjaro-Laptop NetworkManager[555]: <info> [1780963259.2368] Config: added 'psk' value '<hidden>'
Jun 09 09:00:59 Manjaro-Laptop NetworkManager[555]: <info> [1780963259.2372] device (wlp3s0): supplicant interface state: disconnected -> inactive
Jun 09 09:00:59 Manjaro-Laptop NetworkManager[555]: <info> [1780963259.2372] device (p2p-dev-wlp3s0): supplicant management interface state: disconnected -> inactive
Jun 09 09:00:59 Manjaro-Laptop wpa_supplicant[640]: wlp3s0: Trying to associate with SSID 'FiveGHz'
Jun 09 09:00:59 Manjaro-Laptop NetworkManager[555]: <info> [1780963259.2677] device (wlp3s0): supplicant interface state: inactive -> associating
Jun 09 09:00:59 Manjaro-Laptop NetworkManager[555]: <info> [1780963259.2678] device (p2p-dev-wlp3s0): supplicant management interface state: inactive -> associating
...
Jun 09 09:00:59 Manjaro-Laptop wpa_supplicant[640]: wlp3s0: CTRL-EVENT-ASSOC-REJECT bssid=00:00:00:00:00:00 status_code=16
Jun 09 09:00:59 Manjaro-Laptop wpa_supplicant[640]: wlp3s0: Added BSSID 52:41:b9:0a:72:d3 into ignore list, ignoring for 10 seconds
...
Jun 09 09:00:59 Manjaro-Laptop NetworkManager[555]: <info> [1780963259.3421] device (wlp3s0): supplicant interface state: associating -> disconnected
Jun 09 09:00:59 Manjaro-Laptop NetworkManager[555]: <info> [1780963259.3421] device (p2p-dev-wlp3s0): supplicant management interface state: associating -> disconnected
...
Jun 09 09:01:02 Manjaro-Laptop wpa_supplicant[640]: wlp3s0: Removed BSSID 52:41:b9:0a:72:d3 from ignore list (clear)
Jun 09 09:01:02 Manjaro-Laptop wpa_supplicant[640]: wlp3s0: Trying to associate with SSID 'FiveGHz'
Jun 09 09:01:02 Manjaro-Laptop systemd[1]: NetworkManager-dispatcher.service: Deactivated successfully.
Jun 09 09:01:02 Manjaro-Laptop NetworkManager[555]: <info> [1780963262.2141] device (wlp3s0): supplicant interface state: scanning -> associating
Jun 09 09:01:02 Manjaro-Laptop NetworkManager[555]: <info> [1780963262.2147] device (p2p-dev-wlp3s0): supplicant management interface state: scanning -> associating
...
Jun 09 09:01:05 Manjaro-Laptop wpa_supplicant[640]: wlp3s0: Removed BSSID 52:41:b9:0a:72:d3 from ignore list (clear)
Jun 09 09:01:05 Manjaro-Laptop wpa_supplicant[640]: wlp3s0: Trying to associate with SSID 'FiveGHz'
Jun 09 09:01:05 Manjaro-Laptop NetworkManager[555]: <info> [1780963265.5946] device (wlp3s0): supplicant interface state: scanning -> associating
Jun 09 09:01:05 Manjaro-Laptop NetworkManager[555]: <info> [1780963265.5946] device (p2p-dev-wlp3s0): supplicant management interface state: scanning -> associating
Jun 09 09:01:05 Manjaro-Laptop wpa_supplicant[640]: wlp3s0: CTRL-EVENT-ASSOC-REJECT bssid=00:00:00:00:00:00 status_code=16
Jun 09 09:01:05 Manjaro-Laptop wpa_supplicant[640]: wlp3s0: Added BSSID 52:41:b9:0a:72:d3 into ignore list, ignoring for 10 seconds
Jun 09 09:01:05 Manjaro-Laptop NetworkManager[555]: <info> [1780963265.7152] device (wlp3s0): supplicant interface state: associating -> disconnected
Jun 09 09:01:05 Manjaro-Laptop NetworkManager[555]: <info> [1780963265.7153] device (p2p-dev-wlp3s0): supplicant management interface state: associating -> disconnected
...
Jun 09 09:01:14 Manjaro-Laptop NetworkManager[555]: <info> [1780963274.6741] device (wlp3s0): supplicant interface state: disconnected -> scanning
Jun 09 09:01:14 Manjaro-Laptop NetworkManager[555]: <info> [1780963274.6742] device (p2p-dev-wlp3s0): supplicant management interface state: disconnected -> scanning
Jun 09 09:01:19 Manjaro-Laptop wpa_supplicant[640]: wlp3s0: CTRL-EVENT-SSID-REENABLED id=0 ssid="FiveGHz"
Jun 09 09:01:19 Manjaro-Laptop wpa_supplicant[640]: wlp3s0: BSSID 52:41:b9:0a:72:d3 ignore list count incremented to 2, ignoring for 10 seconds
Jun 09 09:01:19 Manjaro-Laptop wpa_supplicant[640]: wlp3s0: Removed BSSID 52:41:b9:0a:72:d3 from ignore list (clear)
Jun 09 09:01:19 Manjaro-Laptop wpa_supplicant[640]: wlp3s0: Trying to associate with SSID 'FiveGHz'
Jun 09 09:01:19 Manjaro-Laptop NetworkManager[555]: <info> [1780963279.5111] device (wlp3s0): supplicant interface state: scanning -> associating
Jun 09 09:01:19 Manjaro-Laptop NetworkManager[555]: <info> [1780963279.5112] device (p2p-dev-wlp3s0): supplicant management interface state: scanning -> associating
Jun 09 09:01:19 Manjaro-Laptop wpa_supplicant[640]: wlp3s0: CTRL-EVENT-ASSOC-REJECT bssid=00:00:00:00:00:00 status_code=16
Jun 09 09:01:19 Manjaro-Laptop wpa_supplicant[640]: wlp3s0: Added BSSID 52:41:b9:0a:72:d3 into ignore list, ignoring for 10 seconds
Jun 09 09:01:19 Manjaro-Laptop wpa_supplicant[640]: wlp3s0: CTRL-EVENT-SSID-TEMP-DISABLED id=0 ssid="FiveGHz" auth_failures=2 duration=20 reason=CONN_FAILED
Jun 09 09:01:19 Manjaro-Laptop NetworkManager[555]: <info> [1780963279.6143] device (wlp3s0): supplicant interface state: associating -> disconnected
Jun 09 09:01:19 Manjaro-Laptop NetworkManager[555]: <info> [1780963279.6143] device (p2p-dev-wlp3s0): supplicant management interface state: associating -> disconnected
Jun 09 09:01:22 Manjaro-Laptop systemd[1]: systemd-hostnamed.service: Deactivated successfully.
Jun 09 09:01:24 Manjaro-Laptop NetworkManager[555]: <warn> [1780963284.1724] device (wlp3s0): Activation: (wifi) association took too long
Jun 09 09:01:24 Manjaro-Laptop NetworkManager[555]: <info> [1780963284.1724] device (wlp3s0): state change: config -> need-auth (reason 'none', managed-type: 'full')
Jun 09 09:01:24 Manjaro-Laptop NetworkManager[555]: <warn> [1780963284.1728] device (wlp3s0): Activation: (wifi) asking for new secrets
Jun 09 09:01:24 Manjaro-Laptop NetworkManager[555]: <info> [1780963284.1740] device (wlp3s0): state change: need-auth -> prepare (reason 'none', managed-type: 'full')
Jun 09 09:01:24 Manjaro-Laptop NetworkManager[555]: <info> [1780963284.1744] device (wlp3s0): state change: prepare -> config (reason 'none', managed-type: 'full')
Jun 09 09:01:24 Manjaro-Laptop NetworkManager[555]: <info> [1780963284.1749] device (wlp3s0): Activation: (wifi) connection 'FiveGHz' has security, and secrets exist. No new secrets needed.
Jun 09 09:01:24 Manjaro-Laptop NetworkManager[555]: <info> [1780963284.1749] Config: added 'ssid' value 'FiveGHz'
Jun 09 09:01:24 Manjaro-Laptop NetworkManager[555]: <info> [1780963284.1750] Config: added 'scan_ssid' value '1'
Jun 09 09:01:24 Manjaro-Laptop NetworkManager[555]: <info> [1780963284.1750] Config: added 'bgscan' value 'simple:30:-70:86400'
Jun 09 09:01:24 Manjaro-Laptop NetworkManager[555]: <info> [1780963284.1750] Config: added 'key_mgmt' value 'WPA-PSK WPA-PSK-SHA256 FT-PSK'
Jun 09 09:01:24 Manjaro-Laptop NetworkManager[555]: <info> [1780963284.1750] Config: added 'auth_alg' value 'OPEN'
Jun 09 09:01:24 Manjaro-Laptop NetworkManager[555]: <info> [1780963284.1751] Config: added 'psk' value '<hidden>'
Jun 09 09:01:24 Manjaro-Laptop NetworkManager[555]: <info> [1780963284.2242] device (wlp3s0): supplicant interface state: disconnected -> scanning
Jun 09 09:01:24 Manjaro-Laptop NetworkManager[555]: <info> [1780963284.2242] device (p2p-dev-wlp3s0): supplicant management interface state: disconnected -> scanning
Jun 09 09:01:26 Manjaro-Laptop wpa_supplicant[640]: wlp3s0: Removed BSSID 52:41:b9:0a:72:d3 from ignore list (clear)
Jun 09 09:01:26 Manjaro-Laptop wpa_supplicant[640]: wlp3s0: Trying to associate with SSID 'FiveGHz'
Jun 09 09:01:27 Manjaro-Laptop NetworkManager[555]: <info> [1780963287.0328] device (wlp3s0): supplicant interface state: scanning -> associating
Jun 09 09:01:27 Manjaro-Laptop NetworkManager[555]: <info> [1780963287.0329] device (p2p-dev-wlp3s0): supplicant management interface state: scanning -> associating
Jun 09 09:01:27 Manjaro-Laptop wpa_supplicant[640]: wlp3s0: CTRL-EVENT-ASSOC-REJECT bssid=00:00:00:00:00:00 status_code=16
Jun 09 09:01:27 Manjaro-Laptop wpa_supplicant[640]: wlp3s0: Added BSSID 52:41:b9:0a:72:d3 into ignore list, ignoring for 10 seconds
Jun 09 09:01:27 Manjaro-Laptop wpa_supplicant[640]: wlp3s0: CTRL-EVENT-SSID-TEMP-DISABLED id=0 ssid="FiveGHz" auth_failures=1 duration=10 reason=CONN_FAILED
Jun 09 09:01:27 Manjaro-Laptop NetworkManager[555]: <info> [1780963287.1041] device (wlp3s0): supplicant interface state: associating -> disconnected
Jun 09 09:01:27 Manjaro-Laptop NetworkManager[555]: <info> [1780963287.1042] device (p2p-dev-wlp3s0): supplicant management interface state: associating -> disconnected
I tried
Mod edit: Consecutive posts merged.