@Kevin_Z 

My ISP is Turknet, and also they checked my internet line connection is fine, I already connected via wired lan and always controlled with wired connection, when wan drops router's led turns the solid white color.

I connected the my device to modem directly for two times and modem working properly. When connection drops LAN IP and Default Gateway is persist as it's supposed to be,

just public wan IP drops to 0.0.0.0 because wan dropped by router.

I already checked the link https://www.tp-link.com/support/faq/2237/  a few days ago but it can not helped, because all connections and configurations are correct.

I am sending all pictures and log file to the attachment.

Btw. I also report the issue to TP-LINK (here in our country) Turkey, they want to send me the router to the service center? oh it's been just 2 weeks and I could not use it anyway, what should I do?

It's annoying...

@Kevin_Z 

I completely gave up and turned off the router, it is dropping the wan connection continuously at the moment,

on previous post I made a mistake about internet connection led turns to orange (not white) and below the screenshot at last state.

@Kevin_Z 

Here is the last situation;

I have replaced the ethernet cable between modem and router (the cable came with router) with another cat5e gigabit cable which I made,

it seems working without problems for about 3 days.

The last state of system log screenshot below.