Are the M2M connections presented as routers in the WAN of the balance ones or are they modems connected via USB?
If WAN connected via a WAN port then all you can really do is either disable health checks or dial down the health check mechanism so it only measures wan health every hour.
If in the USB port you could set its standby state to disconnected when in lower priority.
I assume you have it set to Priority 2 in the speedfusion profile.
Its connected on the WAN ports as router.
WAN-checks are not an issue at all. They do not produce a lot of traffic.
The problem are alive-checks with SpeedFusion tunnels. Although they are set to the highest interval, alive-checks are doing a lot of traffic on every WAN - no matter if active, or not.
It would be great, if the devices would not probe for WAN-errors of standby-connections that often. That does not make sense to me. Active connections should be probed more often, while standy-ones less often.