Cannot connect to Ubuntu BLE servers

[Benedek Kupper]

I'm on Ubuntu 22.04.1 LTS, using bluez 5.65 (built from sources by this guide: https://docs.embeddedts.com/BLE_Examples), and doing the following steps:
1. Run `python3 /usr/local/lib/bluez/test/example-advertisement`
2. Run `/usr/local/lib/bluez/test/example-gatt-server`
3. Use nRF Connect app on Android 9 phone to connect to the "TestAdvertisement" device

The outcome is that the phone app tries to connect, but fails, leaving me with a view of the GATT services and characteristics, but with no way of accessing (read/write/notify) it. I have tried many other BLE server implementations, but for the bug reporting I focused on the most trusted reference.

Full logs are attached. The relevant part of the btmon log is here:
@ MGMT Event: Device Connected (0x000b) plen 13 {0x0001} [hci0] 945.575247
        LE Address: 4D:2C:9A:88:F1:86 (Resolvable)
        Flags: 0x00000000
        Data length: 0
< HCI Command: LE Read Remote Used Features (0x08|0x0016) plen 2 #32 [hci0] 945.575351
        Handle: 3585 Address: 4D:2C:9A:88:F1:86 (Resolvable)
@ RAW Open: btmon (privileged) version 2.22 {0x0002} 945.575453
@ RAW Close: btmon {0x0002} 945.575462
> HCI Event: LE Meta Event (0x3e) plen 4 #33 [hci0] 945.575984
      LE Channel Selection Algorithm (0x14)
        Handle: 3585 Address: 4D:2C:9A:88:F1:86 (Resolvable)
        Algorithm: #1 (0x00)
> HCI Event: LE Meta Event (0x3e) plen 6 #34 [hci0] 945.576990
      LE Advertising Set Terminated (0x12)
        Status: Success (0x00)
        Handle: 1
        Connection handle: 3585
        Number of completed extended advertising events: 0
> HCI Event: Command Status (0x0f) plen 4 #35 [hci0] 945.578094
      LE Read Remote Used Features (0x08|0x0016) ncmd 1
        Status: Unsupported Remote Feature / Unsupported LMP Feature (0x1a)
< HCI Command: Disconnect (0x01|0x0006) plen 3 #36 [hci0] 945.578193
        Handle: 3585 Address: 4D:2C:9A:88:F1:86 (Resolvable)
        Reason: Remote User Terminated Connection (0x13)
> HCI Event: Command Status (0x0f) plen 4 #37 [hci0] 945.579984
      Disconnect (0x01|0x0006) ncmd 1
        Status: Success (0x00)
> HCI Event: Disconnect Complete (0x05) plen 4 #38 [hci0] 945.652123
        Status: Success (0x00)
        Handle: 3585 Address: 4D:2C:9A:88:F1:86 (Resolvable)
        Reason: Connection Terminated By Local Host (0x16)
@ MGMT Event: Device Disconnected (0x000c) plen 8 {0x0001} [hci0] 945.652224
        LE Address: 4D:2C:9A:88:F1:86 (Resolvable)
        Reason: Connection terminated by local host (0x02)

The Additional information:
$ hciconfig -a
hci0: Type: Primary Bus: USB
 BD Address: BC:6E:E2:D0:B1:27 ACL MTU: 1021:4 SCO MTU: 96:6
 UP RUNNING PSCAN
 RX bytes:3074 acl:43 sco:0 events:194 errors:0
 TX bytes:7295 acl:42 sco:0 commands:125 errors:0
 Features: 0xbf 0xfe 0x0f 0xfe 0xdb 0xff 0x7b 0x87
 Packet type: DM1 DM3 DM5 DH1 DH3 DH5 HV1 HV2 HV3
 Link policy: RSWITCH SNIFF
 Link mode: PERIPHERAL ACCEPT
 Name: 'epitos'
 Class: 0x6c010c
 Service Classes: Rendering, Capturing, Audio, Telephony
 Device Class: Computer, Laptop
 HCI Version: (0xc) Revision: 0x3484
 LMP Version: (0xc) Subversion: 0x3484
 Manufacturer: Intel Corp. (2)

$ bluetoothctl
Agent registered
[CHG] Controller BC:6E:E2:D0:B1:27 Pairable: yes
[bluetooth]# show
Controller BC:6E:E2:D0:B1:27 (public)
 Name: epitos
 Alias: epitos
 Class: 0x006c010c
 Powered: yes
 Discoverable: no
 DiscoverableTimeout: 0x000000b4
 Pairable: yes
 UUID: A/V Remote Control (0000110e-0000-1000-8000-00805f9b34fb)
 UUID: Handsfree Audio Gateway (0000111f-0000-1000-8000-00805f9b34fb)
 UUID: PnP Information (00001200-0000-1000-8000-00805f9b34fb)
 UUID: Audio Sink (0000110b-0000-1000-8000-00805f9b34fb)
 UUID: Headset (00001108-0000-1000-8000-00805f9b34fb)
 UUID: A/V Remote Control Target (0000110c-0000-1000-8000-00805f9b34fb)
 UUID: Generic Access Profile (00001800-0000-1000-8000-00805f9b34fb)
 UUID: Audio Source (0000110a-0000-1000-8000-00805f9b34fb)
 UUID: Generic Attribute Profile (00001801-0000-1000-8000-00805f9b34fb)
 UUID: Vendor specific (12345678-1234-5678-1234-56789abcdef0)
 UUID: Device Information (0000180a-0000-1000-8000-00805f9b34fb)
 UUID: Battery Service (0000180f-0000-1000-8000-00805f9b34fb)
 UUID: Heart Rate (0000180d-0000-1000-8000-00805f9b34fb)
 Modalias: usb:v1D6Bp0246d0540
 Discovering: no
 Roles: central
 Roles: peripheral
Advertising Features:
 ActiveInstances: 0x01 (1)
 SupportedInstances: 0x07 (7)
 SupportedIncludes: tx-power
 SupportedIncludes: appearance
 SupportedIncludes: local-name
 SupportedSecondaryChannels: 1M
 SupportedSecondaryChannels: 2M
 SupportedSecondaryChannels: Coded
[bluetooth]# devices
Device 90:00:DB:0D:50:8C SM-G800F
[bluetooth]# info 90:00:DB:0D:50:8C
Device 90:00:DB:0D:50:8C (public)
 Name: SM-G800F
 Alias: SM-G800F
 Class: 0x005a020c
 Icon: phone
 Paired: yes
 Trusted: yes
 Blocked: no
 Connected: no
 LegacyPairing: no
 UUID: OBEX Object Push (00001105-0000-1000-8000-00805f9b34fb)
 UUID: Audio Source (0000110a-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: Headset AG (00001112-0000-1000-8000-00805f9b34fb)
 UUID: PANU (00001115-0000-1000-8000-00805f9b34fb)
 UUID: NAP (00001116-0000-1000-8000-00805f9b34fb)
 UUID: Handsfree Audio Gateway (0000111f-0000-1000-8000-00805f9b34fb)
 UUID: Phonebook Access Server (0000112f-0000-1000-8000-00805f9b34fb)
 UUID: Message Access Server (00001132-0000-1000-8000-00805f9b34fb)
 UUID: PnP Information (00001200-0000-1000-8000-00805f9b34fb)
 UUID: Generic Access Profile (00001800-0000-1000-8000-00805f9b34fb)
 UUID: Generic Attribute Profile (00001801-0000-1000-8000-00805f9b34fb)
 Modalias: bluetooth:v00E0p1200d1436

[Daniel van Vugt (vanvugt)]

Thanks for the bug report. Unfortunately we can't support personal builds of BlueZ here. If you experience any issues with BlueZ that you built yourself then please report them upstream at https://github.com/bluez/bluez/issues