Coexist example does not connect iPhone

[leejh]

Hello, Nordic.

I'm configuring a mesh network. The provisioner, client and server all going well, except for one problem.

I made a client and server based on sdk-coexist, a basic example provided by Nordic. But I can't connect to BLE NUS on iPhoneX, iPhone13.

The enviroment and problems are as follows:

 - current using   : S.E.S Tool / SDK v16.0 / MeshSDK v4.2

 - Testing mobile : iPhone 6 [O] / iPhone 6+ [O] / iPhone X [X] / iPhone 13 [X]

 - problems log

<info> app: Connected
<info> app: Data len is set to 0x42(66)
<error> nrf_ble_gatt: sd_ble_gap_data_length_update() (request) on connection 0x0 returned NRF_ERROR_RESOURCES.
<error> nrf_ble_gatt: The requested TX/RX packet length is too long by 178/178 octets.
<info> app: Disconnected

The iPhone 6, iPhone 6+ and Android Phone are shown same log, but Connection / NUS working well.

But, iPhone X and iPhone 13 cannot connect after the log above (checked in nRF Connect and nRF Toolbox)

I have tested as follow

I will waiting for your reply. thanks

[Mttrinh]

Hi,

Just to clarify, you tested as mentioned in the picture for all of the phones mentioned and only iPhone X and iPhone 13 couldn't connect to the device?

I made a client and server based on sdk-coexist, a basic example provided by Nordic

Is this a custom application based on the coexistence example? Or are you using a modified version of the coexistence example? Are you using a DK?

[leejh]

Sorry for the late reply.

It has been solved, and I think the problem is the config value.

(Before that, I modified it to iPhone12, not iPhone13)

[in app_config.h]

NRF_SDH_BLE_GATT_MAX_MTU_SIZE 69 --> 247

NRF_SDH_BLE_GAP_DATA_LENGTH 251 -->  251

If the MAX_MTU_SIZE and DATA_LENGTH do not differ by 4, an error occurs.

The above values do not cause an error. 

Can you explain to me this situation?

(In addition, Android phones and iPhone 8 under never occur errors. This error occurs only on iPhone8 or later)