IP address problem with Peplink loadbalance


I am using a peplink router to loadbalance 6 internet lines from ISPs with 6 static IP addresses. It is loadbalanced working well.

Now I want to use a Mikrotik router as a hotspot gateway. This mikrotik is connected to the Peplink by a fixed LAN IP address of the Peplink. The Mikrotik router also get one of the ISP static IP address automatically. However, this IP address is always changed among its 6 IP addresses. This thing makes the mikrotik hotspot gateway cannot work properly.

So, could you guys guide me how to config the Peplink so that the Mikrotik get only one IP address?? but the peplink still has loadbalance of the 6 internet lines.

I am waiting for your guide. Thank you!!

Can you provide network diagram with IP addresses to show how the Peplink and Microtik routers were connected?