I don't know if this is the right place for this question but here it goes...
When I access websites that have Google ads included with a device (pc, tablet, laptop) connected to my LAN, these ads are blocked and replaced with other annoying ads from other ad networks. This happens in all web browsers.
But when instead I use my cellphone as wifi hotspot, the Google ads are shown. Is my local area network infected?
I have run several antiviruses and adware cleaners on my network's pc but nothing found. I also have a CISCO router.
The unwanted ads are coming from 188.8.131.52 and ib.adnxs.com. They are replacing only the Google Ads, not my homepage or anything else.