Separate 1Gbps Network

Our office bought Maxis fibre 1Gbps and Unifi fibre 1Gbps.

-When I connect Maxis fibre to WAN 1 port, its got connection and able to access internet

-When I connect Maxis fibre to WAN 2 port, got error DNS address could not be found after try to access Internet

-Same thing : When I connect Unifi fibre to WAN 1 port, its got connection and able to access internet and When I connect Unifi fibre to WAN 2 port, got error DNS address could not be found after try to access Internet

Please advise.

Peplink Model - Peplink 305

You can try to set the DNS to 8.8.8.8 under WAN Connection Settings and see if it will work?