There is depend the WAN type and the product model that you are using.
For Balance series Ethernet WAN/Fiber , if you set the WAN as backup, it will be in disconnected state (Cold Standby)
For Balance Series , Mobile Internet WAN/Cellular, you can set the backup WAN as “Remain connected (Hot Standby) or Disconnect (Cold Standby”
For MAX Series , Ethernet WAN/Cellular/WIFI WAN, you can set the backup WAN as “Remain connected (Hot Standby) or Disconnect (Cold Standby)”
Notes:
- Backup Remain Connected WAN, WAN health check will continue run.
- Backup disconnect WAN , WAN health check will not work or no traffics can be sent.
Hope the explained your question ^^.
WAN heath check reference :