Serial over (classic) bluetooth / COM port can't be open with Windows 11

[Art-ut-Kia]

Board

Wemos D1 R32

Device Description

No external hardware, only the Wemos D1 R32 board attached to the PC (windows 11 laptop) with an USB wire

Hardware Configuration

no connection

Version

latest stable Release (if not listed below)

Type

Bug

IDE Name

Arduino IDE

Operating System

Windows 11

Flash frequency

80MHz

PSRAM enabled

yes

Upload speed

921600

Description

SerialToSerialBT example sketch uploaded.
I succeed to pair the ESP32 with Windows 11, but it is impossible to open the relevant COM port at PC side.
It works well with another PC running Windows 10, as well as with an android phone.

Sketch

SerialToSerialBT.ino

Debug Message

no crash no debug message

Other Steps to Reproduce

Works well when communicating with android device or Windows 10 device

I have checked existing issues, online documentation and the Troubleshooting Guide

• I confirm I have checked existing issues, online documentation and Troubleshooting guide.

[me-no-dev]

If it works with other operating systems, I'd suggest you look for Windows help on the matter. The device obviously works well.

[Art-ut-Kia]

If it works with other operating systems, I'd suggest you look for Windows help on the matter. The device obviously works well.

That makes sense. But I have spent a lot of time to search Windows forums about this issue without any success.
In fact I think it's the Win11/ESP32 combination that is the issue. If Win11 couldn't handle Serial over bluetooth at all, this should be known!

[Jason2866]

Honestly what do you expect? This is Arduino issue repo. Since Windows 10 is working, something in Windows has changed and not working anymore. The BLE implementation is OS agnostic.

[Jason2866]

Windows 11 does BLE serial different!

Windows 11 BLE Serial Support

Windows 11 fundamentally supports Bluetooth Low Energy (BLE) starting with version 22H2 with Bluetooth Core Specification 5.3, however not with the classic Serial Port Profile (SPP) like Bluetooth Classic. Communication via BLE works differently than direct serial connections with Bluetooth Classic.

BLE vs. Bluetooth Classic Serial

With Bluetooth Classic, a virtual COM port is automatically created when you pair an SPP device. With BLE, there is no native SPP support – instead, the GATT protocol (Generic Attribute Profile) is used.

BLE UART via GATT

For serial communication over BLE, GATT-based services like the Nordic UART Service (NuS) are used. This emulates a UART interface via two GATT Characteristics:

• TX Characteristic (0x6E400002) with WRITE permission for data from client to server
• RX Characteristic (0x6E400003) with READ/NOTIFY permission for data from server to client

Practical Solutions

For communicating with BLE UART devices on Windows 11, there are several approaches:

Software Tools for Virtual COM Ports:

• ble-serial: A tool that connects BLE UART modules with virtual serial ports (COM ports), functioning similar to rfcomm bind for Bluetooth Classic
• BLE Serial Terminal: A native Windows application for BLE UART communication that works on Windows 10 and 11

Programmatic Access:

Windows provides APIs for GATT client functionality, allowing you to communicate via BLE Characteristics. Access is through GATT Services and Characteristics instead of classic serial COM ports.

[Art-ut-Kia]

Windows 11 also supports serial over classic bluetooth (SPP). For instance it communicates well with an HC-05.
I would have liked to connect an ESP32 as easily.

[Art-ut-Kia]

I observed that an old version of espressif arduino made my SPP connection work with Windows 11.
But it was rather unstable.