bt_nus_client_send failed (err -120) happend in certain frequency

[Ziyao Zhou]

Hi,

I have twp device: one peripheral and one central. My peripheral is sending out high payload data continiously. And my central is sending data ()in 10Hz frequency. However, every few times  I 'll receive bt_nus_client_send failed (err -120). I noticed that 120 means Operation already in progress. How to solve this issue? Or the central can only sending data very slow.

Whether it is relative to my setting interval=320 (400 ms), latency=0, timeout=400

Thank you for your help!

	 err = bt_nus_client_send(&nus_client, nus_data.data, nus_data.len);
				 if (err) {
					 LOG_WRN("Failed to send data over BLE connection"
						 "(err %d)", err);
				 }