Why two router create problem

Hello friends,

my question is why two router create problem when router A on dhcp mode or other router is non dhcp (dhcp disbled).
and both router are connected two different ISP. and Router A using Tplink and Router B is Netgear giene.

and the problem is some times both connection are stopped working.
Tp link(192.168.1.1) & Netgear (192.168.0.1).

plz friends help ASAP.