fortigate 90D remote access issues

hello experts,

Basically the issue is that i cannot access 90D unit sometimes (when WAN1 is down for any reason)

i have 2 units , one works perfectly fine and DDNS switches to whatever interface is up , also i can manually access it using any of the WLB WAN ip address and looks like that:

the other one have the same type WAN connections(pppoe) but i can only access it when WAN1 is on , even if i manually try to access the unit using any of the other interfaces WAN IP i cannot reach the unit, looks like this:

now as far as i understand HTTPS allowed suppose to make the remote access to the unit possible, or am i missing something?

any help is appreciated.

covered IP addresses and interface names which contain pppoe usernames