[Bug] V6 max 2.4GHz dongle not working with KVM

[sssyao]

Describe the Bug

Hello guys. I recently (Nov 2025) purchased a Keychron V6 max and found that the 2.4GHz dongle cannot work with my UGREEN KVM.

A little bit more context:

1. The 2.4GHz dongle can work when it is directly connected with my laptop.
2. This KVM can work with the 2.4GHz dongle of Logitech MK270 keyboard/mouse combo.
3. I've tried both "keyboard" and "mouse" ports of the KVM and neither of them work.
4. When the 2.4GHz dongle is connected to the KVM, my laptop can detect "Keychron link" (Win 10, under the "Bluetooth & other devices" tab), but the "Keychron link" says "Driver error", and nothing happened as I typed on the keyboard.
5. I've tried to flash a custom firmware by setting MOUSEKEY and NKRO to false in the info.json, and added one line to the ansi_encoder/config.h as suggested by this github thread [Bug] Compile error "'kb_report_changed' undeclared" when disabling NKRO #395 to avoid compile error. But still not working.

Any suggestions would be highly appreciated. Thanks.

Keyboard Used

V6 max

Link to product page (if applicable)

https://www.keychron.com/products/keychron-v6-max-qmk-via-wireless-custom-mechanical-keyboard?srsltid=AfmBOopqrkFv3gAM3dK3rYaG4tlgQtN3wKYg00FvJa2e7ksRYsNN2cK-

Operating System

Windows 10

qmk doctor Output

Is AutoHotKey / Karabiner installed

• AutoHotKey (Windows)
• Karabiner (macOS)

Other keyboard-related software installed

No response

Additional Context

No response

[MachFour]

Is this perhaps the same / similar issue to #391?

[sssyao]

Is this perhaps the same / similar issue to #391?

Hi MachFour. Thank you for referring to this issue. I have actually read that post. My understanding is that the issue there was solved by disabling MOUSEKEY_ENABLE, NKRO_ENABLE and APDAPTIVE_NKRO_ENABLE.

I have set MOUSEKEY and NKRO to false in the info.json. I've added #undef APDAPTIVE_NKRO_ENABLE in conf.h. With that, I think I have done the same thing with the solution provided there, but still could not have 2.4GHz dongle work.

Please correct me if I was wrong or I have missed something. Thanks.

[PeterMortensen]

You may have to use 'qmk clean' (or the equivalent) for changes to the JSON file to take effect.

At least I found it to be necessary for field "device_version" in file info.json (at least in some QMK/source code versions).