Headset: Sony WH-1000XM5 (firmware version 2.5.1)
Mobile Phone: Google Pixel 9
Sound Connect version: 13.0.5 (mobile phone app to interact with headset bluetooth)
CPU: Intel(R) Core(TM) i9-14900K
Motherboard: ASUS ROG STRIX Z790-F GAMING WIFI II
Desktop SW environment: sway, waybar, wayland, pipewire, pipewire-pulse, wireblumber

I am not currently able to connect this headset to my PC.  But, also, see below at the end.

Through the Sound Connect mobile app I am able to use my headset with my mobile when calling or receiving a phone call.

I also own a laptop, also with Arch Linux installed, where I am able to connect the laptop with the headset and it works as it should.  Arch was installed on that laptop around April/May 2025, and using the archinstall script, and not more manually as for my PC around March/April 2024.

More details for the PC bluetooth issue:

After a fresh reboot, the bluetooth service has the following messages:

root@archlinux ~]# systemctl --lines=800 status bluetooth.service 
● bluetooth.service - Bluetooth service
     Loaded: loaded (/usr/lib/systemd/system/bluetooth.service; enabled; preset: disabled)
     Active: active (running) since Thu 2026-05-14 10:03:05 CEST; 3h 16min ago
 Invocation: b6898d8593b642a38d63b716fddfb184
       Docs: man:bluetoothd(8)
   Main PID: 1349 (bluetoothd)
     Status: "Running"
      Tasks: 1 (limit: 231437)
     Memory: 4.1M (peak: 4.1M)
        CPU: 63ms
     CGroup: /system.slice/bluetooth.service
             └─1349 /usr/lib/bluetooth/bluetoothd

mai 14 10:03:05 archlinux systemd[1]: Starting Bluetooth service...
mai 14 10:03:05 archlinux bluetoothd[1349]: Bluetooth daemon 5.86
mai 14 10:03:05 archlinux bluetoothd[1349]: Starting SDP server
mai 14 10:03:05 archlinux systemd[1]: Started Bluetooth service.
mai 14 10:03:05 archlinux bluetoothd[1349]: Bluetooth management interface 1.23 initialized
mai 14 10:03:05 archlinux bluetoothd[1349]: Battery Provider Manager created
mai 14 10:03:05 archlinux bluetoothd[1349]: Failed to set default system config for hci0
mai 14 10:06:58 archlinux bluetoothd[1349]: Endpoint registered: sender=:1.30 path=/MediaEndpoint/A2DPSource/ldac
mai 14 10:06:58 archlinux bluetoothd[1349]: Endpoint registered: sender=:1.30 path=/MediaEndpoint/A2DPSink/aptx_hd
mai 14 10:06:58 archlinux bluetoothd[1349]: Endpoint registered: sender=:1.30 path=/MediaEndpoint/A2DPSource/aptx_hd
mai 14 10:06:58 archlinux bluetoothd[1349]: Endpoint registered: sender=:1.30 path=/MediaEndpoint/A2DPSink/aptx
mai 14 10:06:58 archlinux bluetoothd[1349]: Endpoint registered: sender=:1.30 path=/MediaEndpoint/A2DPSource/aptx
mai 14 10:06:58 archlinux bluetoothd[1349]: Endpoint registered: sender=:1.30 path=/MediaEndpoint/A2DPSink/aac
mai 14 10:06:58 archlinux bluetoothd[1349]: Endpoint registered: sender=:1.30 path=/MediaEndpoint/A2DPSource/aac
mai 14 10:06:58 archlinux bluetoothd[1349]: Endpoint registered: sender=:1.30 path=/MediaEndpoint/A2DPSink/opus_g
mai 14 10:06:58 archlinux bluetoothd[1349]: Endpoint registered: sender=:1.30 path=/MediaEndpoint/A2DPSource/opus_g
mai 14 10:06:58 archlinux bluetoothd[1349]: Endpoint registered: sender=:1.30 path=/MediaEndpoint/A2DPSink/sbc
mai 14 10:06:58 archlinux bluetoothd[1349]: Endpoint registered: sender=:1.30 path=/MediaEndpoint/A2DPSource/sbc
mai 14 10:06:58 archlinux bluetoothd[1349]: Endpoint registered: sender=:1.30 path=/MediaEndpoint/A2DPSource/aptx_ll_1
mai 14 10:06:58 archlinux bluetoothd[1349]: Endpoint registered: sender=:1.30 path=/MediaEndpoint/A2DPSource/aptx_ll_0
mai 14 10:06:58 archlinux bluetoothd[1349]: Endpoint registered: sender=:1.30 path=/MediaEndpoint/A2DPSource/aptx_ll_duplex_1
mai 14 10:06:58 archlinux bluetoothd[1349]: Endpoint registered: sender=:1.30 path=/MediaEndpoint/A2DPSource/aptx_ll_duplex_0
mai 14 10:06:58 archlinux bluetoothd[1349]: Endpoint registered: sender=:1.30 path=/MediaEndpoint/A2DPSource/faststream
mai 14 10:06:58 archlinux bluetoothd[1349]: Endpoint registered: sender=:1.30 path=/MediaEndpoint/A2DPSource/faststream_duplex
mai 14 10:06:58 archlinux bluetoothd[1349]: Endpoint registered: sender=:1.30 path=/MediaEndpoint/A2DPSink/opus_05
mai 14 10:06:58 archlinux bluetoothd[1349]: Endpoint registered: sender=:1.30 path=/MediaEndpoint/A2DPSource/opus_05
mai 14 10:06:58 archlinux bluetoothd[1349]: Endpoint registered: sender=:1.30 path=/MediaEndpoint/A2DPSink/opus_05_duplex
mai 14 10:06:58 archlinux bluetoothd[1349]: Endpoint registered: sender=:1.30 path=/MediaEndpoint/A2DPSource/opus_05_duplex
mai 14 10:07:05 archlinux bluetoothd[1349]: Endpoint unregistered: sender=:1.30 path=/MediaEndpoint/A2DPSource/ldac
mai 14 10:07:05 archlinux bluetoothd[1349]: Endpoint unregistered: sender=:1.30 path=/MediaEndpoint/A2DPSink/aptx_hd
mai 14 10:07:05 archlinux bluetoothd[1349]: Endpoint unregistered: sender=:1.30 path=/MediaEndpoint/A2DPSource/aptx_hd
mai 14 10:07:05 archlinux bluetoothd[1349]: Endpoint unregistered: sender=:1.30 path=/MediaEndpoint/A2DPSink/aptx
mai 14 10:07:05 archlinux bluetoothd[1349]: Endpoint unregistered: sender=:1.30 path=/MediaEndpoint/A2DPSource/aptx
mai 14 10:07:05 archlinux bluetoothd[1349]: Endpoint unregistered: sender=:1.30 path=/MediaEndpoint/A2DPSink/aac
mai 14 10:07:05 archlinux bluetoothd[1349]: Endpoint unregistered: sender=:1.30 path=/MediaEndpoint/A2DPSource/aac
mai 14 10:07:05 archlinux bluetoothd[1349]: Endpoint unregistered: sender=:1.30 path=/MediaEndpoint/A2DPSink/opus_g
mai 14 10:07:05 archlinux bluetoothd[1349]: Endpoint unregistered: sender=:1.30 path=/MediaEndpoint/A2DPSource/opus_g
mai 14 10:07:05 archlinux bluetoothd[1349]: Endpoint unregistered: sender=:1.30 path=/MediaEndpoint/A2DPSink/sbc
mai 14 10:07:05 archlinux bluetoothd[1349]: Endpoint unregistered: sender=:1.30 path=/MediaEndpoint/A2DPSource/sbc
mai 14 10:07:05 archlinux bluetoothd[1349]: Endpoint unregistered: sender=:1.30 path=/MediaEndpoint/A2DPSource/aptx_ll_1
mai 14 10:07:05 archlinux bluetoothd[1349]: Endpoint unregistered: sender=:1.30 path=/MediaEndpoint/A2DPSource/aptx_ll_0
mai 14 10:07:05 archlinux bluetoothd[1349]: Endpoint unregistered: sender=:1.30 path=/MediaEndpoint/A2DPSource/aptx_ll_duplex_1
mai 14 10:07:05 archlinux bluetoothd[1349]: Endpoint unregistered: sender=:1.30 path=/MediaEndpoint/A2DPSource/aptx_ll_duplex_0
mai 14 10:07:05 archlinux bluetoothd[1349]: Endpoint unregistered: sender=:1.30 path=/MediaEndpoint/A2DPSource/faststream
mai 14 10:07:05 archlinux bluetoothd[1349]: Endpoint unregistered: sender=:1.30 path=/MediaEndpoint/A2DPSource/faststream_duplex
mai 14 10:07:05 archlinux bluetoothd[1349]: Endpoint unregistered: sender=:1.30 path=/MediaEndpoint/A2DPSink/opus_05
mai 14 10:07:05 archlinux bluetoothd[1349]: Endpoint unregistered: sender=:1.30 path=/MediaEndpoint/A2DPSource/opus_05
mai 14 10:07:05 archlinux bluetoothd[1349]: Endpoint unregistered: sender=:1.30 path=/MediaEndpoint/A2DPSink/opus_05_duplex
mai 14 10:07:05 archlinux bluetoothd[1349]: Endpoint unregistered: sender=:1.30 path=/MediaEndpoint/A2DPSource/opus_05_duplex
[root@archlinux ~]#

I think all the "Endpoint unregistered" lines indicates some trouble some where, but where?  One answer from google was to restart the bluetooth service, but afterwards both all the "Endpoint registered" and all the "Endpoint unregistered" was lost:

[root@archlinux 20260514]# systemctl --lines=800 status bluetooth.service 
● bluetooth.service - Bluetooth service
     Loaded: loaded (/usr/lib/systemd/system/bluetooth.service; enabled; preset: disabled)
     Active: active (running) since Thu 2026-05-14 16:39:05 CEST; 10min ago
 Invocation: b13ce16e75b74a11ad5874c80b0db475
       Docs: man:bluetoothd(8)
   Main PID: 52293 (bluetoothd)
     Status: "Running"
      Tasks: 1 (limit: 231437)
     Memory: 1.3M (peak: 2.7M)
        CPU: 46ms
     CGroup: /system.slice/bluetooth.service
             └─52293 /usr/lib/bluetooth/bluetoothd

mai 14 16:39:05 archlinux systemd[1]: Starting Bluetooth service...
mai 14 16:39:05 archlinux bluetoothd[52293]: Bluetooth daemon 5.86
mai 14 16:39:05 archlinux systemd[1]: Started Bluetooth service.
mai 14 16:39:05 archlinux bluetoothd[52293]: Starting SDP server
mai 14 16:39:05 archlinux bluetoothd[52293]: Bluetooth management interface 1.23 initialized
mai 14 16:39:05 archlinux bluetoothd[52293]: Battery Provider Manager created
mai 14 16:39:05 archlinux bluetoothd[52293]: Failed to set default system config for hci0
[root@archlinux 20260514]# 

On my laptop, I see only all the "Endpoint registered" lines (and no "Endpoint unregistered" lines), which seems more correctly.

Here is a listing of what happens when I try to connect my headset to my PC:

1. Stop the bluetooth service.

2. Remove possible previous/old/cached blutetooth connections/entries/config by running

   [root@archlinux 20260514]# rm -rf /var/lib/bluetooth/*

3. Start the bluetooth service again:

   [root@archlinux 20260514]# systemctl --lines=800 start bluetooth.service 
   [root@archlinux 20260514]# systemctl --lines=800 status bluetooth.service 
   ● bluetooth.service - Bluetooth service
        Loaded: loaded (/usr/lib/systemd/system/bluetooth.service; enabled; preset: disabled)
        Active: active (running) since Thu 2026-05-14 17:03:34 CEST; 6s ago
    Invocation: 7373a04ba395421c8d75016c50803086
          Docs: man:bluetoothd(8)
      Main PID: 57460 (bluetoothd)
        Status: "Running"
         Tasks: 1 (limit: 231437)
        Memory: 1.5M (peak: 2.7M)
           CPU: 37ms
        CGroup: /system.slice/bluetooth.service
                └─57460 /usr/lib/bluetooth/bluetoothd
   
   mai 14 17:03:34 archlinux systemd[1]: Starting Bluetooth service...
   mai 14 17:03:34 archlinux bluetoothd[57460]: Bluetooth daemon 5.86
   mai 14 17:03:34 archlinux systemd[1]: Started Bluetooth service.
   mai 14 17:03:34 archlinux bluetoothd[57460]: Starting SDP server
   mai 14 17:03:34 archlinux bluetoothd[57460]: Bluetooth management interface 1.23 initialized
   mai 14 17:03:34 archlinux bluetoothd[57460]: Battery Provider Manager created
   mai 14 17:03:34 archlinux bluetoothd[57460]: Failed to set default system config for hci0
   [root@archlinux 20260514]# 

4. Now using chapter "2 Pairing" from https://wiki.archlinux.org/title/Bluetooth and the bluetoothctl example, I get the following:

   [userxxxx@archlinux ~]$ /usr/bin/bluetoothctl 
   [NEW] Media /org/bluez/hci0 
           SupportedUUIDs: 0000110a-0000-1000-8000-00805f9b34fb
           SupportedUUIDs: 0000110b-0000-1000-8000-00805f9b34fb
   Agent registered
   [bluetoothctl]> agent KeyboardOnly 
   Agent is already registered
   [bluetoothctl]> default-agent 
   Default agent request successful
   [bluetoothctl]> power on
   Changing power on succeeded
   [bluetoothctl]> show
   Controller 99:99:99:99:99:99 (public)
           Manufacturer: 0x0002 (2)
           Version: 0x0d (13)
           Name: archlinux
           Alias: archlinux
           Class: 0x00000104 (260)
           Powered: yes
           PowerState: on
           Discoverable: no
           DiscoverableTimeout: 0x000000b4 (180)
           Pairable: yes
           UUID: Generic Attribute Profile (00001801-0000-1000-8000-00805f9b34fb)
           UUID: Generic Access Profile    (00001800-0000-1000-8000-00805f9b34fb)
           UUID: PnP Information           (00001200-0000-1000-8000-00805f9b34fb)
           UUID: A/V Remote Control Target (0000110c-0000-1000-8000-00805f9b34fb)
           UUID: A/V Remote Control        (0000110e-0000-1000-8000-00805f9b34fb)
           UUID: Device Information        (0000180a-0000-1000-8000-00805f9b34fb)
           Modalias: usb:v1D6Bp0246d0556
           Discovering: no
           Roles: central
           Roles: peripheral
   Advertising Features:
           ActiveInstances: 0x00 (0)
           SupportedInstances: 0x0c (12)
           SupportedIncludes: tx-power
           SupportedIncludes: appearance
           SupportedIncludes: local-name
           SupportedSecondaryChannels: 1M
           SupportedSecondaryChannels: 2M
           SupportedSecondaryChannels: Coded
           SupportedCapabilities.MinTxPower: 0xffffffd8 (-40)
           SupportedCapabilities.MaxTxPower: 0x000f (15)
           SupportedCapabilities.MaxAdvLen: 0xfb (251)
           SupportedCapabilities.MaxScnRspLen: 0xfb (251)
           SupportedFeatures: CanSetTxPower
           SupportedFeatures: HardwareOffload
   [bluetoothctl]> 

5. First make sure that possible previous paired atempts from my mobile phone is deleted. Doing this by "Cancel Registration" within the "Sound Connect" app, and then rebooting my mobile afterwards.

6. Then I use the "Sound Connect" app from my mobile using "Connect to New Device", which results in the sound "pinging" from my headset.

7. First error: Then running the commands "scan on" and "pair 11:22:33:44:55:66" to pair my headset.

   bluetoothctl]> scan on
   SetDiscoveryFilter success
   Discovery started
   [CHG] Controller 99:99:99:99:99:99 Discovering: yes
   [NEW] Device 11:22:33:44:55:66 WH-1000XM5
   <<<deleted similar lines for privacy reasons>>>
   [bluetoothctl]> pair 11:22:33:44:55:66 
   Attempting to pair with 11:22:33:44:55:66
   [CHG] Device 11:22:33:44:55:66 Connected: yes
   [CHG] Device 11:22:33:44:55:66 Bonded: yes
   [CHG] Device 11:22:33:44:55:66 UUIDs: 00000000-deca-fade-deca-deafdecacaff
   [CHG] Device 11:22:33:44:55:66 UUIDs: 00001108-0000-1000-8000-00805f9b34fb
   [CHG] Device 11:22:33:44:55:66 UUIDs: 0000110b-0000-1000-8000-00805f9b34fb
   [CHG] Device 11:22:33:44:55:66 UUIDs: 0000110c-0000-1000-8000-00805f9b34fb
   [CHG] Device 11:22:33:44:55:66 UUIDs: 0000110d-0000-1000-8000-00805f9b34fb
   [CHG] Device 11:22:33:44:55:66 UUIDs: 0000110e-0000-1000-8000-00805f9b34fb
   [CHG] Device 11:22:33:44:55:66 UUIDs: 0000110f-0000-1000-8000-00805f9b34fb
   [CHG] Device 11:22:33:44:55:66 UUIDs: 0000111e-0000-1000-8000-00805f9b34fb
   [CHG] Device 11:22:33:44:55:66 UUIDs: 00001124-0000-1000-8000-00805f9b34fb
   [CHG] Device 11:22:33:44:55:66 UUIDs: 00001131-0000-1000-8000-00805f9b34fb
   [CHG] Device 11:22:33:44:55:66 UUIDs: 00001200-0000-1000-8000-00805f9b34fb
   [CHG] Device 11:22:33:44:55:66 UUIDs: 2573f2dd-a2f8-486c-8476-a63734909acb
   [CHG] Device 11:22:33:44:55:66 UUIDs: 45c93e07-d90d-4b93-a9db-91e5dd734e35
   [CHG] Device 11:22:33:44:55:66 UUIDs: 764cbf0d-bbcb-438f-a8bb-6b92759d6053
   [CHG] Device 11:22:33:44:55:66 UUIDs: 81c2e72a-0591-443e-a1ff-05f988593351
   [CHG] Device 11:22:33:44:55:66 UUIDs: 8901dfa8-5c7e-4d8f-9f0c-c2b70683f5f0
   [CHG] Device 11:22:33:44:55:66 UUIDs: 931c7e8a-540f-4686-b798-e8df0a2ad9f7
   [CHG] Device 11:22:33:44:55:66 UUIDs: 956c7b26-d49a-4ba8-b03f-b17d393cb6e2
   [CHG] Device 11:22:33:44:55:66 UUIDs: 9b26d8c0-a8ed-440b-95b0-c4714a518bcc
   [CHG] Device 11:22:33:44:55:66 UUIDs: df21fe2c-2515-4fdb-8886-f12c4d67927c
   [CHG] Device 11:22:33:44:55:66 UUIDs: f76acb00-7cab-495f-bb1a-e664598fd77f
   [CHG] Device 11:22:33:44:55:66 UUIDs: f7a96061-a1b3-40de-aff0-e78ec45a151e
   [CHG] Device 11:22:33:44:55:66 UUIDs: f8d1fbe4-7966-4334-8024-ff96c9330e15
   [CHG] Device 11:22:33:44:55:66 ServicesResolved: yes
   [CHG] Device 11:22:33:44:55:66 Paired: yes
   Pairing successful
   [CHG] Device 11:22:33:44:55:66 WakeAllowed: yes
   [CHG] Device 11:22:33:44:55:66 ServicesResolved: no
   [SIGNAL] BREDR.Disconnected - org.bluez.Reason.Local, Connection terminated by local host
   [SIGNAL] Disconnected - org.bluez.Reason.Local, Connection terminated by local host
   [CHG] Device 11:22:33:44:55:66 Connected: no
   [bluetoothctl]> scan off
   Discovery stopped
   [bluetoothctl]> trust 11:22:33:44:55:66 
   [CHG] Device 11:22:33:44:55:66 Trusted: yes
   Changing 11:22:33:44:55:66 trust succeeded
   [bluetoothctl]> 

   The "Sound Connect" app from my mobile said "connection canceled" if I remember correctly, and when returning a new entry is listed under "Paired" with expected name = "archlinux".

8. If I now from the "Sound Connect" app click on the "archlinux" line, it says "connecting" and after 1-2 seconds a message says "Connection with archlinux failed.".  And I get some more lines in the bluetoothctl prompt:

   [CHG] Device 11:22:33:44:55:66 Connected: yes
   [SIGNAL] BREDR.Disconnected - org.bluez.Reason.Remote, Connection terminated by remote user
   [SIGNAL] Disconnected - org.bluez.Reason.Remote, Connection terminated by remote user
   [CHG] Device 11:22:33:44:55:66 Connected: no
   [CHG] Device 11:22:33:44:55:66 Connected: yes
   [SIGNAL] BREDR.Disconnected - org.bluez.Reason.Remote, Connection terminated by remote user
   [SIGNAL] Disconnected - org.bluez.Reason.Remote, Connection terminated by remote user
   [CHG] Device 11:22:33:44:55:66 Connected: no
   [bluetoothctl]> 

9. If I now run the command "connect 11:22:33:44:55:66" from my Arch Linux PC, I get this:

   [bluetoothctl]> connect 11:22:33:44:55:66 
   Attempting to connect to 11:22:33:44:55:66
   [CHG] Device 11:22:33:44:55:66 Connected: yes
   Connection successful
   [CHG] Device 11:22:33:44:55:66 ServicesResolved: yes
   [WH-1000XM5]> info 11:22:33:44:55:66 
   Device 11:22:33:44:55:66 (public)
           Name: WH-1000XM5
           Alias: WH-1000XM5
           Class: 0x00240404 (2360324)
           Icon: audio-headset
           Paired: yes
           Bonded: yes
           Trusted: yes
           Blocked: no
           Connected: yes
           WakeAllowed: yes
           LegacyPairing: no
           CablePairing: no
           UUID: Vendor specific           (00000000-deca-fade-deca-deafdecacaff)
           UUID: Headset                   (00001108-0000-1000-8000-00805f9b34fb)
           UUID: Audio Sink                (0000110b-0000-1000-8000-00805f9b34fb)
           UUID: A/V Remote Control Target (0000110c-0000-1000-8000-00805f9b34fb)
           UUID: Advanced Audio Distribu.. (0000110d-0000-1000-8000-00805f9b34fb)
           UUID: A/V Remote Control        (0000110e-0000-1000-8000-00805f9b34fb)
           UUID: A/V Remote Control Cont.. (0000110f-0000-1000-8000-00805f9b34fb)
           UUID: Handsfree                 (0000111e-0000-1000-8000-00805f9b34fb)
           UUID: Human Interface Device... (00001124-0000-1000-8000-00805f9b34fb)
           UUID: Headset HS                (00001131-0000-1000-8000-00805f9b34fb)
           UUID: PnP Information           (00001200-0000-1000-8000-00805f9b34fb)
           UUID: Vendor specific           (2573f2dd-a2f8-486c-8476-a63734909acb)
           UUID: Vendor specific           (45c93e07-d90d-4b93-a9db-91e5dd734e35)
           UUID: Vendor specific           (764cbf0d-bbcb-438f-a8bb-6b92759d6053)
           UUID: Vendor specific           (81c2e72a-0591-443e-a1ff-05f988593351)
           UUID: Vendor specific           (8901dfa8-5c7e-4d8f-9f0c-c2b70683f5f0)
           UUID: Vendor specific           (931c7e8a-540f-4686-b798-e8df0a2ad9f7)
           UUID: Vendor specific           (956c7b26-d49a-4ba8-b03f-b17d393cb6e2)
           UUID: Vendor specific           (9b26d8c0-a8ed-440b-95b0-c4714a518bcc)
           UUID: Vendor specific           (df21fe2c-2515-4fdb-8886-f12c4d67927c)
           UUID: Vendor specific           (f76acb00-7cab-495f-bb1a-e664598fd77f)
           UUID: Vendor specific           (f7a96061-a1b3-40de-aff0-e78ec45a151e)
           UUID: Vendor specific           (f8d1fbe4-7966-4334-8024-ff96c9330e15)
           Modalias: usb:v054Cp0DF0d0251
   [WH-1000XM5]>

   And it stays in this state.  But no change from my "Sound Connect" app from my mobile.

10. I get one extra message line from the bluetooth.service after doing the above (as I did not check after each step, I cannot tell which step):

    mai 14 17:40:37 archlinux bluetoothd[57460]: src/service.c:btd_service_connect() a2dp-sink profile connect failed for 11:22:33:44:55:66: Protocol not available

I google'ed the extra message line from above, and I ended up setting these 2 variables to just do some test:

[root@archlinux ~]# grep --invert-match --extended-regexp "^#|^[ ]*$"  /etc/bluetooth/main.conf
[General]
Experimental = true
KernelExperimental = true
[BR]
[LE]
[GATT]
[CSIS]
[AVDTP]
[AVRCP]
[Policy]
[AdvMon]
[root@archlinux ~]# 

and rebooted the PC, but still I see all the "Endpoint unregistered" lines from bluetooth.service after a fresh reboot.

I must mention that in the summer of 2024 I was able to get the headset connected 1 or 2 times, but not stable as in "after each and every reboot".  Do not remember exactly all details here.  Long time ago.

Last time I was successfull was for some few months ago, where I removed the following 2 .so files (moved them to a backup dir).  I was maybe suspecting that some pulseaudio files was left somewhere, and that fact would maybe do some harm:

/usr/lib/pulseaudio/libpulsedsp.so
/usr/lib/pulseaudio/libpulsecommon-17.0.so

did not manage to get a stable lasting solution this time either.

But, sine I use waybar, and it depends on these 2 .so files:

[root@archlinux removed_pulseaudo_files_and_dirs]# ldd /usr/bin/waybar | grep --ignore-case pulse
	libpulse.so.0 => /usr/lib/libpulse.so.0 (0x00007f2903cfd000)
	libpulsecommon-17.0.so => /usr/lib/pulseaudio/libpulsecommon-17.0.so (0x00007f2902a4c000)
[root@archlinux removed_pulseaudo_files_and_dirs]# 

it seems like a solution which is not good in the long run!  :-)

I have over a long time been trying several times to fix this issue, but have not been able to get a (stable) solution.  I have installed and uninstalled several files/packages here and there, to try several things.   Only guessing here, but maybe some config/installed file did not cleanly got installed/uninstalled?

PS!  the 2 MAC addresses "11:22:33:44:55:66" and "99:99:99:99:99:99" are masked values for privacy reasons.