There is a wrong in the comments in ble_ll_sched.h
From the Bluetooth Core Spec 5.1, Vol6, PartB, Page2696
The maximum adv package len is 257( 2 Bytes Header + 255 Bytes Payload)
@@ -48,7 +48,7 @@ extern "C" {
#define BLE_LL_SCHED_MAX_ADV_PDU_USECS (376)
/* We don't know how big aux packet will be. It depends on adv packet len which
- * can be up to 256. For now we fix it to 128 bytes, but we can optimize it.
+ * can be up to 257. For now we fix it to 128 bytes, but we can optimize it.
*/
#define BLE_LL_SCHED_AUX_PTR_DFLT_BYTES_NUM (128)
