Double NAT Internet Access Problem

Installing and Using OpenWrt Network and Wireless Configuration
1

Hello everyone,

Few days ago I flashed openwrt to two of my routers Archer A7 and TL-WR940N V2. Flashing and setup went fine but after that my internet connection started to randomly drop out. Sometimes I cant access the internet at all and sometimes I can ping websites but chrome says that connection timed out.

Here's my setup
ZTE F620 Fiber Router from ISP (192.168.1.1) - Dns Servers (1.1.1.1 and 8.8.8.8)
Archer A7 (192.168.1.3) 192.168.0.1
wr940n 192.168.0.2 (Wireless Access Point)

rebooting zte router solves the problem, also directly plugging into the zte router with another device seems to resolve the issue
so my questions are

  1. How can I diagnose which device is messing up and
  2. How can I get out of double NAT and keep openwrt as my only router
2

Put the zte in a bridge mode, then just use OpenWrt router as your router. Only works if zte firmware has a bridge mode

3

It seems that ISP router does not have support for bridge mode is there any way to configure it manually?

4

I followed this tutorial lets see if it fixes my problems