Error 8 (0x8) GATT CONN TIMEOUT On Android

[why_do_i_need_a_user_name]

NRF51422 Custom board

SD310 v3.0

Phone: LG K8 4G

Android 6.0

SDK 9.0.0 Boot-loader example

I am testing over the air DFU with our custom device.

a.) DFU using NRF Toolbox on IPhone works fine.

b.) DFU using MCP\NRF51 dongle works fine.

c.) DFU using NRF Toolbox on Android fails with "upload failed GATT error"

nRFConnect on Android can connect with our device but loses the connection after about 6 seconds and the logger captures the following error:

Error 8 (0x8) GATT CONN TIMEOUT

[Hung Bui]

It's normal that increasing the preferred connection parameter will make DFU process slower and this will affect all other master devices.

I would need to have a sniffer trace recording (with the original connection parameter) to see what exactly caused the problem.

I was suspecting that there is a buffer overflow here because the connection was too short, but normally it should be OK with 15ms interval.

I assume you have the same problem when testing with the original bootloader.

[Aser]

Hi I am currently working on the same TIMEOUT error during the same DFU progress. In the meantime, I posted a question on the Dev zone and found this post while waiting for a reply.
As I mentioned above, I changed the interval as shown in the picture below, but still the TIMEOUT error occurred and DFU did not succeed.
Could you help me with this problem?