Throughput ATT_MTU

[Ridhi]

We are using nrf52832 soc for our product development and using that we are trying to increase the throughput of our device using the information from the following forum:
Novel Bits throughput guide 
In this forum it states that the Maximum GATT MTU SIZE possible is 247 bytes in which 244 bytes of data is the actual payload size and if the data is greater than the limit, then it will split into multiple packets. So we tried to send more that 247 bytes of data just to check how the data split in multiple packet is working. We tried to sent 256 bytes of data and we were able to get 255 bytes of data without any splitting, which is more than 247 bytes. So we are wondering what is the Maximum GATT MTU SIZE possible in nrf52832 soc. 
We also looked into the throughput example provided by the nordic (ble_app_att_mtu) and in that MTU size is set to 247 and data length is set to 251 which is less that what we are able to send from nrf52832 to phone, is there any possible explanation for this?

[Simonr]

Hi

You're looking at the L2CAP protocol, and in the sniffer trace you can see that the length comes after multiple L2CAP fragments before this notification. You see that the length of payload captured by the BLE sniffer is 38 bytes, and that the L2CAP fragments are reassembled from 10 different packets.

Best regards,

Simon

[Ridhi]

i have sent 252 bytes of data. then what is this 38bytes payload can you tell me. 

[Ridhi]

actually simon, i want to know all about:

1). if i am sendinf 252 bytes from peripheral side then, how will this data be received in fragments on notification,

2). i used power profiler kit PPK2 for ble_att_throughput example that multiple packets were formed per connection interval.

3). in my case but i am only  able to get one packet per connection interval why is it so pls help