If you have your primary at the remote location, that means that your network subnets off that controller is local to that subnet. So if you bring up another wlc as a backup for the remote site, but located in another location, you will have to have the dynamic interface(s) in the backup location.
For example, if wifi users on the remote site gets a dhcp of 192.168.50.x when the primary is up, then the wifi users will have to get dhcp from another subnet, but from the backup location.
Hope this makes sense.
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