Device setting is not working

Please post screenshot of Settings/Viewports.

https://snag.gy/Yxu8th.jpg
https://snag.gy/CSlcIo.jpg
Please check these screenshots.In the first one you’ll find I have selected only phone in device.
In the second screenshot you’ll see the ad unit is also showing on dekstops.
Please help to resolve this problem asap.

Actually I wanted to see the screenshot of Ad Inserter Settings/Viewports (tab *, tab Viewports).

It seems that your website doesn’t have CSS code for viewports.
It should be iserted inline in the page HTML header.

Something like this:

<style id='ai-frontend-inline-css' type='text/css'>
.ai-viewport-3                { display: none !important;}
.ai-viewport-2                { display: none !important;}
.ai-viewport-1                { display: inherit !important;}
.ai-viewport-0                { display: none !important;}
@media (min-width: 768px) and (max-width: 979px) {
.ai-viewport-1                { display: none !important;}
.ai-viewport-2                { display: inherit !important;}
}
@media (max-width: 767px) {
.ai-viewport-1                { display: none !important;}
.ai-viewport-3                { display: inherit !important;}
}

</style>

Please post the screenshot of Viewports settings.

Here is the screenshot of viewport.

I want to tell you this problem is occurring in all of my websites from last one month. Which are using different themes and previously plugin is working fine with all the sites.

The settings seem ok.

Device detection doesn’t work because your website doesn’t have CSS code for viewports (see above).
Ad Inserter inserted it as inline CSS code in the page HTML header but something (theme/plugin) removed that code.

Please try to disable caching to see if the code appears.

I put that above code you mention in the header and it works. But is that code is accurate for different screen sizes.

Yes, the code is generted and inserted by Ad Inserter according to Viewport settings.

I would still try to figure out what is causing the removal of the code.