Hello, I'm using NRF52832 with SoftDevice S132, and SDK 14.0.0 to make NUS peripheral and central. To test it I have one NUS peripheral device, that echoes incoming data, one NUS peripheral and central device that forwards incoming data, and nrf51 dongle with nRF Connect to test it. I use dongle to connect to peripheral/central device. Peripheral/central device connects to periheral only device. I send data with nRF Connect to peripheral/central device, it sends it to peripheral device, periheral sends it back to peripheral/central, and this one should forward it to nRF Connect. Problem is when peripheral/central gets data back from peripheral and tries to to send it to nRF Connect. Function sd_ble_gatts_hvx() returns 0x3401 code. Using sd_ble_gatts_value_set() does not help. For debugging I made peripheral/central to send back to nRF connect some dummy data before forwarding received data. As long as peipheral was not connected to peripheral/central, dummy data was send back properly. Only after connection between peripheral and peripheral/central is established, 0x3401 is happening. To make this program I used SDK example for NUS central, SDK example for NUS peripheral and SDK example for central and peripheral hrs/rscs relay.
Apparently problem exists only if periheral connects to peripheral/central after nRF Connect connects to to peripheral/central. If nRF connects second, everything works fine.