Idea for a new feature in either the GUI or CLI (preferably both)-- allow restricting which network interfaces are used for backup.
The use case for this idea is that people sometimes tether to their mobile device when away from WiFi, but given the cost and bandwidth limitations of tethering, they might not want to use for backup.
ARQ Backup has a similar feature called “Use Specific Network Interfaces”, referenced on this page: Restricting Network Usage