You should be able to run a traceroute to see where it's blocked/timing out along the way.
If you open up a command window (if your windows has a 'search' or 'run' option on the menu, type cmd.exe). Once there, type:
It will tell you the path of the connection and where it's getting stuck.
If you're using a Mac you still can, but you go about it differently.
(Don't screenshot and post it here because it will reveal your IP address). If it's getting stuck before it reaches Pinterest and doesn't continue from that point, it should give you an idea.