Just a note on a problem we had yesterday on our PI Server. Hopefully it can help someone else.
Each time we had to restart a service or reboot the server, users could not reconnect to the server, they would get a timeout error or unable to connect to the server. We stopped and started the PI Server and did a bunch of stuff without really knowing what we were doing. After 30 minutes or so, the server accepted connections again.
That problem started just after our upgrade to 3.4.375.80 which happened at the same time of our migration to AD. Guess what. Our clients were using the NT 4 DNS and the servers the AD DNS.
We put back the PI Server on NT4 DNS and the problem disappeared.
When client migration is done, we will change the server back to AD DNS.