How to setup LAN to WAN connection between two routers

I have two routers which I want to establish a LAN to WAN connection. my primary router (router: TP LINK WR840N ) LAN settings IP: 192.168.0.1 DHCP: enabled Subnet Mask: 255.255.255.0 Now for the first time when I connected the LAN to the secondary router's (router: TENDA N300 ) WAN (which was more than a year ago), it showed the connection status to dynamic, and it worked on its own. Now after a year, the connection of secondary router was not working properly. After hard reset, it is now showing static IP. What I have done I reset the secondary router again, and it is still showing that it h

Question by tanjim anim on Super User, licensed CC BY-SA. We show a short excerpt and link to the original thread as credit.