MAX BR1 LTE. Access WAN Web Interface through local network

Dear all,
Need some help to configure the following:
On a MAX BR1 a WAN Router connected on WAN port.
The WAN router provides a Range of IPs (ex. 192.168.0.2-192.168.0.5) while the web interface of it is accessible to 192.168.0.1.
The Peplink network is the default 192.168.50.1.
what kind of rules muast be applied on PEPWAVE so the computers from the local network (192.168.50.0/24) to access the WAN WEB interface?