What to know
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The Depot Bus is unlocked from the AIC Factory Plan (your AIC tech tree), not by crafting a standalone item.
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You’ll need AIC Index (skill points) to buy the required nodes, earned by interacting with Protocol Dataloggers found across the map.
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The quest step typically points you back to your hub/central base area to use a specific panel/menu to access the AIC Factory Plan.
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Depot Bus is a major factory quality-of-life upgrade because it improves how you move items in and out of your Depot and supports more flexible production layouts.
When the AIC Steward asks you to “unlock the Depot Bus,” Arknights: Endfield is really testing whether you understand how Endfield’s AIC progression works – explore for tech points, spend them in the Factory Plan, then come back and expand what your base can do. Here’s how to unlock the Depot Bus.
| Item | Quick details |
|---|---|
| Quest | AIC Steward (includes the “unlock Depot Bus” objective). |
| Where you unlock it | AIC Factory Plan (tech tree) via the hub/base panel/menu. |
| What you need | AIC Index (skill points) from Protocol Dataloggers. |
| What it enables | Logistics Bus access for moving items in/out of the Depot; enables Bus Loaders/Bus Unloaders after the related expansion unlock. |
| Why it matters | Frees your factory layouts from relying only on limited Automated Core ports and makes production lines cleaner and more scalable. |
How the Depot Bus fits your base progression
The AIC Factory Plan is your tech tree for factory development, with each node unlocking a technology, building, or capability used in your Core AIC Area. In the Basic AIC Factory Plan, the “Expansion I” node explicitly states that the Logistics Bus can be used to move items in and out of the Depot and that you can construct Bus Loaders and Bus Unloaders.
Locations involved
You’ll bounce between two kinds of places:
- Your central hub/base (to access the AIC Factory Plan panel and apply the unlock)
- The open-world regions (to find Protocol Dataloggers that grant the AIC Index you need).
How to unlock the Depot Bus for the AIC Steward quest
Step 1: Confirm the quest objective and pin the unlock point
Open the AIC Steward quest and verify it specifically requires “unlock Depot Bus,” because this tells you the next action is in the AIC tech tree rather than on a crafting bench.
Follow the marker back to the hub/central base area where the AIC interface panel is located.
Step 2: Return to the hub and access the AIC Factory Plan panel
Go back to the central hub and interact with the special panel.
The objective points you toward to open the AIC Factory Plan menu.
In this menu, you’ll be viewing your AIC technologies and development tree, where each node represents an unlockable AIC technology.
Step 3: Check your available AIC Index (skill points)
Before buying anything, look at how many points you currently have available to spend in the AIC Factory Plan. These points come from Protocol Dataloggers (also referred to as Protocol Dataloggers in base-building explanations), which are scattered around the map and can be located via the world map.
Step 4: If you’re short on points, farm Protocol Dataloggers
Open your world map and look for the Protocol Datalogger markers/icons.
Then travel to them and interact to collect AIC Index. These are spread across regions, so if one area looks cleared out, check other regions for additional Dataloggers.
Step 5: Spend points along the required path to reach Depot Bus
Back in the AIC Factory Plan, follow the path down the relevant branch until you reach the Depot Bus unlock node required for the quest step. If your tree doesn’t let you select the Depot Bus node immediately, unlock prerequisite nodes along the same path first (the quest expects you to “work your way down” to that exact node).
Step 6: Unlock the node and advance the quest
Purchase the Depot Bus node once you have the required AIC Index, then exit the menu and verify the quest updates to the next step.
If it doesn’t advance, re-check that you unlocked the correct node and not a similarly named logistics/expansion upgrade.
Step 7: Start using Depot Bus benefits in your factory planning
After unlocking Depot Bus, you’ll generally want to integrate bus-based logistics so your production lines aren’t constrained by the limited Automated Core/Sub-PAC ports. This upgrade is repeatedly highlighted as a “massive improvement” for making cleaner, more compact layouts that scale better as your factory grows.
How to avoid common blockers
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If the quest says “unlock Depot Bus” but you can’t find it, you’re likely not looking in the AIC Factory Plan tree or you’re not on the correct branch/path to the node.
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If you’re missing points, don’t grind random combat—focus on Protocol Dataloggers since they directly provide the Basic AIC Index used for tech unlocks.
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If your factory feels “capped” early (not enough outputs/ports), that limitation is exactly why the AIC Steward quest and Depot Bus upgrade exist in the first place.
Treat the Depot Bus unlock as a short loop: return to hub → open AIC Factory Plan → confirm you have enough AIC Index → if not, collect Protocol Dataloggers → buy the Depot Bus node and continue the quest.
