I have some project which worked without problem. After updating I faced at first time one problem with Ping() and later second this problem.
trying get network stream:
var newStream = stream.GetRequestStream();
I got this:
But in OS Windows this code work excellent.
You can see video here https://www.dropbox.com/s/x62wvmkmj5pl7qo/out-1.ogv?dl=0
*** This bug has been marked as a duplicate of bug 41782 ***