A VOOL charger and an LMC can be connected over CAN and LAN at the same time. Understanding how each side picks its channel explains one of the most common load-management problems we see in support.
How the channel is chosen
On the LMC, switching is automatic. If CAN is available, it is always preferred. If CAN is not available and LAN is, the LMC uses LAN.
On the charger, the channel is fixed configuration. The charger only accepts load management on the control channels that have been explicitly enabled in its settings ("enabled control channels"). It does not follow the LMC's automatic switching.
There is no fallback in the sense installers usually mean it. Having both a CAN cable and a shared network does not give you an active channel and a spare one. The LMC will simply use whichever it prefers at that moment, and the charger will accept it only if that channel is enabled.
The failure this causes
Because the LMC switches automatically but the charger does not, the two can end up on different channels:
CAN drops for some reason (loose cable, wiring fault, interference). The LMC switches to LAN — but if LAN is not an enabled control channel on the charger, the charger deliberately rejects load management from there, and load management stops working even though both devices are online.
The same happens the other way around. If someone sets the charger's load management to LAN only, and CAN communication later comes back, the LMC switches back to its preferred CAN — and the charger rejects load management over CAN.
A recognisable version of this: charging works on the day of installation with the charger set to LAN, then fails the next day and only works again once the charger is set back to CAN. Nothing broke — the LMC changed channel and the charger did not.
Auto-configuration can change the channel for you
Running auto-configuration may set the charger's load-management communication to LAN. That is worth knowing before you use it as a fix, for two reasons:
If the site is wired for CAN and you auto-configure, you may end up with the charger expecting LAN while the LMC prefers CAN.
If auto-configuration appears to fix a site, check afterwards which channel it settled on, so the next person is not surprised.
One combination that is always wrong
If a charger communicates with the LMC over LAN, its OCPP source must not be set to LMC. That combination is invalid, and the portal will not always stop you from saving it.
The OCPP source is a separate question from the control channel, and it is the one most often set wrong. See Charger's OCPP Source for which value to use.
If you are wiring CAN
Chargers are chained: the CAN cable runs from one charger to the next.
The last charger in the chain needs its termination resistor fitted. A chain without termination — or terminated in the wrong place — produces intermittent communication that looks like a configuration fault.
On long chains, a break part-way along can leave the earlier chargers working and the later ones silent, which makes the fault look like it belongs to individual devices rather than to the bus.
How to recognise it
Both the LMC and the charger show as online, but charging is limited, stuck, or "Suspended by charger".
Warnings about charger–LMC communication or misconfigured load management appear in the portal.
The problem started around the time a cable was changed, a connector was reseated, or someone changed the charger's connectivity settings.
How to fix it
Check the charger's enabled control channels in its settings and make sure every channel the LMC can actually reach the charger on — CAN and/or LAN — is enabled there.
If both a CAN cable and a LAN connection exist between the LMC and the charger, enable both control channels on the charger, so the LMC's automatic switching always lands on an accepted channel.
Confirm the OCPP source is not set to LMC on a charger that talks to the LMC over LAN.
If only one channel is intended to be used, make sure the physical setup matches: an unused CAN link that comes and goes will keep pulling the LMC back to CAN.
After changing the configuration, verify on the site overview at app.vool.com that the charger–LMC communication is healthy, then test a charging session.
If load management still fails after the control channels match on both sides, contact VOOL support with the LMC and charger serial numbers — we can check from the logs which channel each side is trying to use.