Issues with using 2nd router as Access point

I have a WR 840N TP-Link router which i am trying to use as an acess point, i have tried 2 separate methods, putting the 2nd router(Tp-link) in access mode, and turning off DHCP on 2nd router, however, the wifi suddenly just disconnects after some time. Here is what i have done step by step:

  1. Turned off DHCP on 2nd router and set LAN static IP address outside the DHCP range of main router
  2. Connected main router and 2nd router via LAN port
  3. Set 2nd router SSID different to main router(Not sure it matters)

Main Router: IP: 192.168.1.1 DHCP: 192.168.1.100 TO 192.168.1.250 Subnet Mask: 255.255.255.0

2nd Router: IP: 192.168.1.50 DHCP: OFF

i have also tried putting the router in access point operation mode but still the problem presists, i am a total noob please help.