@NazmulHossain 

It would be best to set a 5 to 1 ratio for your 2 connections to prevent saturating the 100mbps connection while there is available bandwidth on the 500mbps (i.e. 5 for the 500mbps connection, 1 for the 100mbps connection)

Then make sure under primary WAN you select both WAN and WAN/LAN1 as your primary WANs. As it is currently set up in your screenshot it will route all traffic through your WAN connection and only fallback to WAN/LAN1 if WAN goes offline. If you have a third back-up you can put that as the back-up WAN, but otherwise leave that empty as it will automatically route all traffic through the remaining WAN if one of your 2 connections go down.
 

  @KimcheeGUN Thank you so much. 

  @ACMiller Thank you so much.