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[OpenArm Troubleshooting] CAN Interface Missing After Reboot on New Control PC (Beginner)

CAN worked once then vanished after reboot? Verify boot order, module load timing, and interface naming before touching hardware.

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A common OpenArm bringup problem appears on a fresh control PC: CAN works once, then after reboot the expected interface name is gone, the device binds differently, or the startup script can no longer find the bus.

How are you diagnosing OpenArm cases where the CAN interface goes missing after reboot on a new control PC?

Please share how you verify driver loading, interface naming, and startup ordering, and what checks help you distinguish a simple host setup issue from cable or transceiver trouble.

If you reply, include one exact reboot symptom and one exact host-side check that exposed the root cause.

Related troubleshooting path: SocketCAN missing after NetworkManager update · No such device on can0 after adapter swap

Module: OpenArm · Audience: builders-integrators · Type: question

Tags: openarm, can, reboot, control-pc

Comment 1

Beginner context: In our case can0 existed right after manual setup, but disappeared after every reboot and OpenArm startup timed out. That told us this was boot ordering, not a dead transceiver.

Comment 2

Beginner context: The check that cracked it was `journalctl -b | rg -n "can|socketcan|modprobe"`. Modules loaded after our startup unit, so the interface was queried too early and never retried.

Comment 3

Beginner context: We added a dedicated `openarm-can.service` with explicit `After=systemd-modules-load.service` and a readiness probe on `ip link show can0`. Reboot reliability has been 100% for three weeks.

Comment 4

Beginner context follow-up: Follow-up question for beginners: can you share your exact boot-time check order (3-5 commands) so another team can confirm CAN readiness before launching OpenArm?

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Quick FAQ

What is the fastest reboot diagnostic path?

Check module load, interface presence, then service order before touching wiring.

lsmod | rg -i "can|socketcan|peak"
ip -details link show can0
journalctl -b | rg -n "can|socketcan|modprobe"
How do I keep it stable across reboots?

Add a dedicated CAN startup unit with explicit dependencies and a readiness gate on can0.

Can I copy these commands as-is?

Use them as a checklist template first. Confirm interface names, fixture IDs, and safety conditions in your own cell before execution.