On my Ubuntu 22.04 I have problems with an external Edimax BT-8500 Bluetooth USB adapter.
When the system boots, it is recognized as hci0, but on usage of a BLE connection it suddenly (after some minutes) is resetting and sometimes it comes back as hci1. After disconnecting and reconnecting or rebooting the OS, it is again hci0 and it works again for some minutes.
root@tsccarport:/home/lukas# hciconfig -a hci0: Type: Primary Bus: USB BD Address: 08:BE:AC:43:06:7A ACL MTU: 1021:6 SCO MTU: 255:12 UP RUNNING RX bytes:11041 acl:0 sco:0 events:350 errors:0 TX bytes:35140 acl:0 sco:0 commands:364 errors:0 Features: 0xff 0xff 0xff 0xfe 0xdb 0xfd 0x7b 0x87 Packet type: DM1 DM3 DM5 DH1 DH3 DH5 HV1 HV2 HV3 Link policy: RSWITCH HOLD SNIFF PARK Link mode: PERIPHERAL ACCEPT Name: 'RTK_BT_5.0' Can't read class of device on hci0: Connection timed out (110) root@tsccarport:/home/lukas# lsusb Bus 001 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 001 Device 002: ID 7392:c611 Edimax Technology Co., Ltd Edimax Bluetooth Ada pter Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 004 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 005 Device 003: ID 0cf3:3000 Qualcomm Atheros Communications AR3011 Bluetoot h (no firmware) Bus 006 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 007 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 008 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 009 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub root@tsccarport:/home/lukas# bluetoothctl Waiting to connect to bluetoothd...[bluetooth]# hci1 new_settings: powered bondable ssp br/edr le secure-conn [bluetooth]# Agent registered [bluetooth]# [CHG] Controller 08:BE:AC:43:06:7A Pairable: yes [bluetooth]# power off [bluetooth]# hci1 class of device changed: 0x000000 [bluetooth]# hci1 new_settings: bondable ssp br/edr le secure-conn [bluetooth]# Changing power off succeeded [bluetooth]# [CHG] Controller 08:BE:AC:43:06:7A Powered: no [bluetooth]# [CHG] Controller 08:BE:AC:43:06:7A Discovering: no [bluetooth]# [CHG] Controller 08:BE:AC:43:06:7A Class: 0x00000000 (0) [bluetooth]# power on [bluetooth]# hci1 class of device changed: 0x6c0104 [bluetooth]# [CHG] Controller 08:BE:AC:43:06:7A Class: 0x006c0104 (7078148) [bluetooth]# hci1 new_settings: powered bondable ssp br/edr le secure-conn [bluetooth]# Changing power on succeeded [bluetooth]# [CHG] Controller 08:BE:AC:43:06:7A Powered: yes [bluetooth]# exit root@tsccarport:/home/lukas# hciconfig -a hci1: Type: Primary Bus: USB BD Address: 08:BE:AC:43:06:7A ACL MTU: 1021:6 SCO MTU: 255:12 UP RUNNING RX bytes:2422 acl:0 sco:0 events:236 errors:0 TX bytes:34675 acl:0 sco:0 commands:236 errors:0 Features: 0xff 0xff 0xff 0xfe 0xdb 0xfd 0x7b 0x87 Packet type: DM1 DM3 DM5 DH1 DH3 DH5 HV1 HV2 HV3 Link policy: RSWITCH HOLD SNIFF PARK Link mode: PERIPHERAL ACCEPT Name: 'extern' Class: 0x6c0104 Service Classes: Rendering, Capturing, Audio, Telephony Device Class: Computer, Desktop workstation HCI Version: 5.1 (0xa) Revision: 0xdfc6 LMP Version: 5.1 (0xa) Subversion: 0xd922 Manufacturer: Realtek Semiconductor Corporation (93)after a power off and on it was hci1 after a reboot again hci0.dmesg | grep Bluetooth[ 2356.461990] Bluetooth: hci0: Opcode 0x2037 failed: -22 [ 2358.492834] Bluetooth: hci0: command tx timeout [ 2476.484234] Bluetooth: hci0: Opcode 0x2037 failed: -22 [ 2478.495910] Bluetooth: hci0: command tx timeout [ 3796.514513] Bluetooth: hci0: Opcode 0x2037 failed: -22 [ 3798.519938] Bluetooth: hci0: command tx timeout [ 3826.502536] Bluetooth: hci0: Opcode 0x2037 failed: -22 [ 3828.536370] Bluetooth: hci0: command tx timeout [ 3856.505997] Bluetooth: hci0: Opcode 0x2037 failed: -22 [ 3858.552820] Bluetooth: hci0: command tx timeout [ 3858.552884] Bluetooth: hci0: Resetting usb device. [ 3858.555020] Bluetooth: hci0: urb 0000000023fd0d3f failed to resubmit (2) [ 3858.871969] Bluetooth: hci1: RTL: examining hci_ver=0a hci_rev=dfc6 lmp_ver=0a lmp_subver=d922 [ 3859.086080] Bluetooth: hci1: RTL: examining hci_ver=0a hci_rev=000b lmp_ver=0a lmp_subver=8761 [ 3859.088137] Bluetooth: hci1: RTL: rom_version status=0 version=1 [ 3859.088177] Bluetooth: hci1: RTL: loading rtl_bt/rtl8761bu_fw.bin [ 3859.095589] Bluetooth: hci1: RTL: loading rtl_bt/rtl8761bu_config.bin [ 3859.096760] Bluetooth: hci1: RTL: cfg_sz 6, total sz 30210 [ 3859.399093] Bluetooth: hci1: RTL: fw version 0xdfc6d922 [ 3859.513187] Bluetooth: MGMT ver 1.22```Why is that?