A very similar (Identical) problem to something I experienced in 2014. First of all I see a notable reduction in Adsense income over the long term average.
Then I notice 1 advert in particular is very slow to load, and I get the message in the bottom corner saying looking up V4.moatads.
The page takes about 30 - 60 seconds to completely load. Other ads arent clickable untill the page loads fully. Please see attachment. Any ideas ? This has happened twice now. It cleared up for a few months and my adsense went back to normal levels or even better. Now its started again.
Please see screen shot and note left tower ad not loaded, and bottom left of screen it says looking up v4.moatads.
