Client able to receive 2 packets at 7.5 ms connection interval but fails to receive 2 packets at 20ms

[bale11]

I have a nordic nrf52832 dev board acting as peripheral and  my client device is huawei honor 9 lite. I'm trying to send two packets (or 45 Bytes data) in one connection interval. I have made all the necessary changes to increase the att mtu to 247. I'm able to send data at connection interval 7.5 without any "NRF_ERROR_RESOURCES" error. When I change the connection interval to 20ms I get NRF_ERROR_RESOURCE. 

Why does this happen. If it supports 2 packets at 7.5ms connection interval then it should be the same overall right?

I'm attaching my wireshark file of both 7.5 ms and 20 ms. Any kind of guidance will be helpful

honor_ble_conn_7.5ms_bytes_22.pcapng     honor_ble_conn_20ms_bytes_22.pcapng

[Sigurd]

Hi,

From the sniffer-log I see that the slave is sending 2 packets each connection interval when using 20ms CI, 1 L2CAP fragment and 1 notification. You could try to increase the NRF_SDH_BLE_GAP_EVENT_LENGTH to e.g. 320, and see if you are able to send more packets. You can find the NRF_SDH_BLE_GAP_EVENT_LENGTH in sdk_config.h

[bale11]

Thanks , I'll try that an let you know