- Cellular connectivity from a local network to the internet.
- High Availability employing two cellular-based Peplink routers (HD2 IP67 in the case that brought this to a head)
- Each router connecting to two cellular networks, the two routers employing different carriers, and the carriers requiring specific APNs, which would differ among the two routers.
- Configuration Sync. is active.
The cellular configurations get synchronized from the master to the slave, overwriting the carrier-specific settings of the slave (e.g., APNs, the carrier selection (AT&T v. generic v. Verizon…)).
Active synch cannot be employed, since the slave cannot connect given the cellular settings inherited from the master.
To add insult to injury, it seems that without active synch the SpeedFusion connections do not carry over when the slave becomes master - which is not a happy state.
I expect this to be the case for all WAN settings, and the utility of a redundancy of two HA routers+ISPs is diminished if the two ISPs have conflicting connection settings requirements.
That the WAN settings be optional w.r.t. the active synch feature, i.e., the slave may optionally retain its WAN settings when it is synched, and may benefit from their use when the slave takes on the master role.