Please excuse me if this question is off-topic.
None of the Windows machines(1*Vista, 1*Win7, 1*Win8) on my network can access microsoft.com or AV-sites unless I set 188.8.131.52 as DNS-server. The strange thing with this is that Androids, iOS and Linux devices can access these sites. I tried taking the Win7 laptop to another network (same ISP), and there it managed to access microsoft.com.
I cannot find anything useful on my Thomson TG784 Gateway.
This is a mystery.