getting max S132 connectivity fw throughput

Question

Hi, 
 I'm trying to transmit data at about 500kbps from custom nRF52 board (peripheral, s132 v5, SDK14.0) to a PCA10040 board with a connectivity FW (based on v3.0.1) connected to a PC and pc-ble-driver (central). 
 Currently, with the max throughput settings, 
 
 ATT MTU at 247, 
 PDU at 251, 
 tried conn interval at different settings (11.25, 15, 30, 45), 
 max event length at 320 (on both sides) 
 hvn_tx_queue_size (on peripheral side) at 20 
 transmitting 2 packets of 240 bytes in size every ~8ms 
 
 I can reach 40 KBps (320 kbps). 
 I keep getting NRF_ERROR_RESOURCES from sd_ble_gatts_hvx on the peripheral side. I'm not sure where the bottleneck is or whether it's bad configuration. 
 Any known issues with the connectivity FW? Could this be feasible? 
 I'll appreciate the help.

Bjørn Kvaale · Answer

I have asked the developers of the pc_ble_driver to take a look at this case. Before I start asking you to start trying different things, I think it would be easier if they gave you some tips, as they are more experienced in regards to this firmware. 
 Update: As stated in this devzone case , the bottleneck in this case is the relaying of the UART via the JLink OB. The throughput via the pc_ble_driver will be quite low because of this. If you have a logic analyzer, you will be able to see the traffic over the UART lines & see more of the data flow between the pc & the connectivity FW.