I cannot shift to the smallest sprockets when in the small chain ring
11-speed Di2 road bikes (with BT-DN110 battery / BM-DN100 battery mount) feature a mechanism called Gear Position Control - it prevents you from shifting into the two smallest sprockets when in the little ring.
Gear Position Control also exists on 12-speed Dura-Ace bikes, but not for 12-speed Ultegra and 105.
Want to learn more about Gear Position Control? Here is my guide to Gear Position Control.