I can't figure out why ADV_EXT_IND can not be both scannable and connectable?
Below messages are captured from Bluetooth Core Spec v5.2 (released 12/31/2019) Volume 6, Part B, Section 2.3.1.5 ADV_EVT_IND (page 2875):
The ADV_EXT_IND PDU uses the Common Extended Advertising Payload Format described in Section 2.3.4. The PDU may be used in all advertising events (except connectable and scannable undirected) as indicated by the AdvMode field value. An advertising event using an ADV_EXT_IND PDU is directed if, and only if, either the TargetA field is present or the AuxPtr field is present and points to a PDU where the TargetA field is present.
From Section 2.3.4
Link to Bluetooth Core Specification Download: https://www.bluetooth.com/specifications/bluetooth-core-specification/