L2CAP fragmentation on Windows

[itecnet]

• bleak version: 0.22.3
• Python version: 3.13
• Operating System: Windows10/11

Description

I have a BLE communication from PC to a Nordic MCU (NUS Service) and use Bleak. My application works perfectly under Linux. If I copy my application to Windows (without changes), I get a strong fragmentation of the user data. The only difference is the operating system and the BLE adapter (Linux: Intel AX211 , Windows: EDIMAX BT-8500).

What I Did

I use a standard MTU (517) with data length extension and each packet has a payload of 242 bytes per PDU.
Unfortunately I am new to Windows, but maybe someone can give me a tip on how to remove the fragmentation. I need to transfer 600 kB and the time difference between Linux and Windows is way too big.

Logs

I have attached a Wireshark dump because I could not find a cause.

bleak-win.zip

[dlech]

This is happening at the OS level, so probably not anything we can do about it from Bleak.

Not sure what else to suggest other than trying a different Bluetooth adapter that uses a different driver.