Am on Win10 64bit Insider 11102 rs1 160113-1800

Just within the past few days began to get a series of seemingly related errors accessing the internet. Using the latest Firefox I got "secure connection failed" or "connection reset" errors either when initially entering a URL or after a page had started loading and presumably was pulling something in from another site. Not all websites are affected and sometimes Edge would access them or Edge would report "can't reach this page".

I ended up doing a clean install of Win10 and before installing any other software I tried Edge. It immediately started misbehaving as above. I installed Firefox and it too behaved as before. Not always the same sites. On YouTube for example Firefox will load the main content but won't play HTML5 video. (I don't have Flash installed).

On the BBC news site using Edge, a flash video stays blank. Right clicking it say video not loaded.

I thought at least part of the problem was DNS lookup so I changed the default from my ISP to a third party. Twice. Makes no difference. I ran various netsh and ipconfig commands with no change. My lan driver is the latest.

I am going mad!!