I also am having this issue. Tried the above and deleted the “s” and even deleted my live writer blog account and started again.
I can upload a post to live writer, edit and publish but I get this “Network connection error” as above. The post gets published and looks as intended but I still have this error message displayed every time.
I did not have a problem until I changed templates. Tried to revert back to old template but error appears again. Very annoying!!