sysinfo;lan;access point;web interface;issue

Hi ! First, let me quickly explain my config: Main router (LAN4) <-----------> (WAN) Secondary router (LAN4) <-------------> (LAN) Main computer (Wireless) <-----------> (Wireless) LAP201402 (...) <-----------> (...) Both routers are RT-AC66U with Asus Merlin 380.59. The secondary is...