Windows connection problems

[nrbrook]

We've built a device with the nRF5 17.1.0 SDK on nRF52832 which operates as a HID keyboard. On iOS and Android this is working fine, and it's working fine sometimes on Windows, but not all the time, particularly on slower machines, so I'm trying to figure out what is failing. I've used the Bluetooth Virtual Sniffer (https://docs.microsoft.com/en-gb/windows-hardware/drivers/bluetooth/testing-btp-tools-btvs) to get a packet trace which I've attached (Wireshark). This is from when it is working fine as I can't reproduce the issues locally, but I'm still seeing a number of error responses such as to this find by type value request:

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119 23.654527 localhost () c0:7d:0e:48:3b:0b (BT500S-6 v3.0.7-b.1 FAA6) ATT 18 Sent Find By Type Value Request, GATT Primary Service Declaration, Handles: 0x000e..0xffff

XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

119	23.654527	localhost ()	c0:7d:0e:48:3b:0b (BT500S-6 v3.0.7-b.1 FAA6)	ATT	18	Sent Find By Type Value Request, GATT Primary Service Declaration, Handles: 0x000e..0xffff

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128 23.715589 c0:7d:0e:48:3b:0b (BT500S-6 v3.0.7-b.1 FAA6) localhost () ATT 14 Rcvd Error Response - Attribute Not Found, Handle: 0x000e (Unknown)

XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

128	23.715589	c0:7d:0e:48:3b:0b (BT500S-6 v3.0.7-b.1 FAA6)	localhost ()	ATT	14	Rcvd Error Response - Attribute Not Found, Handle: 0x000e (Unknown)

Why would the softdevice send that response? It seems windows is requesting primary services in a range 0xe to 0xffff - all my services are primary services in that range, but the SD returns attribute not found. For info, here is my list of attributes:

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0x0E (14): Service Battery handle

0x10 (16): Service Battery Characteristic Battery value handle

0x11 (17): Service Battery Characteristic Battery CCCD handle

0x25 (37): Service AT State handle

0x27 (39): Service AT State Characteristic Digital port state value handle

0x28 (40): Service AT State Characteristic Digital port state CCCD handle

0x2A (42): Service AT State Characteristic Analog port state value handle

0x2B (43): Service AT State Characteristic Analog port state CCCD handle

0x2D (45): Service AT State Characteristic Device mode value handle

0x2E (46): Service AT State Characteristic Device mode CCCD handle

0x2F (47): Service AT Charging handle

0x31 (49): Service AT Charging Characteristic Charging state value handle

0x32 (50): Service AT Charging Characteristic Charging state CCCD handle

0x33 (51): Service AT Info handle

0x35 (53): Service AT Info Characteristic Mode features value handle

0x37 (55): Service AT Info Characteristic Digital availability value handle

0x39 (57): Service AT Info Characteristic Analog availability value handle

0x3E (62): Service AT Info Characteristic Pairing state value handle

0x3F (63): Service AT Info Characteristic Pairing state CCCD handle

0x40 (64): Service AT OTA handle

0x42 (66): Service AT OTA Characteristic SDK version value handle

XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

0x0E (14): Service Battery handle
0x10 (16): Service Battery Characteristic Battery value handle
0x11 (17): Service Battery Characteristic Battery CCCD handle
0x25 (37): Service AT State handle
0x27 (39): Service AT State Characteristic Digital port state value handle
0x28 (40): Service AT State Characteristic Digital port state CCCD handle
0x2A (42): Service AT State Characteristic Analog port state value handle
0x2B (43): Service AT State Characteristic Analog port state CCCD handle
0x2D (45): Service AT State Characteristic Device mode value handle
0x2E (46): Service AT State Characteristic Device mode CCCD handle
0x2F (47): Service AT Charging handle
0x31 (49): Service AT Charging Characteristic Charging state value handle
0x32 (50): Service AT Charging Characteristic Charging state CCCD handle
0x33 (51): Service AT Info handle
0x35 (53): Service AT Info Characteristic Mode features value handle
0x37 (55): Service AT Info Characteristic Digital availability value handle
0x39 (57): Service AT Info Characteristic Analog availability value handle
0x3E (62): Service AT Info Characteristic Pairing state value handle
0x3F (63): Service AT Info Characteristic Pairing state CCCD handle
0x40 (64): Service AT OTA handle
0x42 (66): Service AT OTA Characteristic SDK version value handle
0x43 (67): Service AT Parameters handle
0x45 (69): Service AT Parameters Characteristic Connection control value handle
0x46 (70): Service AT Programming handle
0x48 (72): Service AT Programming Characteristic Digital port config value handle
0x4A (74): Service AT Programming Characteristic Digital port config max length value handl
0x4C (76): Service AT Programming Characteristic Analog port config value handle
0x4E (78): Service AT Programming Characteristic Delay before repeat value handle
0x50 (80): Service AT Programming Characteristic Repeat rate value handle
0x52 (82): Service AT Programming Characteristic Idle power off value handle
0x54 (84): Service AT Programming Characteristic Connection configuration value handle
0x56 (86): Service AT Programming Characteristic Pairing method value handle
0x58 (88): Service AT Programming Characteristic Debounce time value handle
0x5A (90): Service AT Programming Characteristic OEM value handle
0x5C (92): Service AT Programming Characteristic Analog input config value handle
0x5E (94): Service AT Programming Characteristic Analog action value handle
0x5F (95): Service MIDI handle
0x61 (97): Service MIDI Characteristic MIDI value handle
0x62 (98): Service MIDI Characteristic MIDI CCCD handle
0x63 (99): Service HID handle
0x65 (101): Service HID Characteristic Protocol mode value handle
0x67 (103): Service HID Characteristic Output report 0 value handle
0x68 (104): Service HID Characteristic Output report 0 CCCD handle
0x74 (116): Service HID Characteristic Output report 0 report reference handle
0x6B (107): Service HID Characteristic Output report 0 value handle
0x6C (108): Service HID Characteristic Output report 0 CCCD handle
0x74 (116): Service HID Characteristic Output report 0 report reference handle
0x6F (111): Service HID Characteristic Output report 0 value handle
0x70 (112): Service HID Characteristic Output report 0 CCCD handle
0x74 (116): Service HID Characteristic Output report 0 report reference handle
0x73 (115): Service HID Characteristic Output report 0 value handle
0x74 (116): Service HID Characteristic Output report 0 report reference handle
0x76 (118): Service HID Characteristic Report map value handle
0x78 (120): Service HID Characteristic Boot kb input value handle
0x79 (121): Service HID Characteristic Boot kb input CCCD handle
0x7B (123): Service HID Characteristic Boot kb output value handle
0x7D (125): Service HID Characteristic Boot mouse input value handle
0x7E (126): Service HID Characteristic Boot mouse input CCCD handle
0x80 (128): Service HID Characteristic Information value handle
0x82 (130): Service HID Characteristic Control point value handle

https://devzone.nordicsemi.com/cfs-file/__key/support-attachments/beef5d1b77644c448dabff31668f3a47-427ce2ba20f9407cba3f41fb7cbbf9d0/trace.pcapng

[nrbrook]

On further inspection I see that the value field in the request is 0118, i.e. 0x1801, i.e. Generic Attribute service, which isn't in that range so the SD returns not found. I'll continue investigating the issue.