Network Cable unplug of the server

I want to share A Practical experience of mine.
yesterday, we install (patch of sun solaries spark) OS patch to our production
Database.

It takes at least four hours, after this we shutdown our oracle Database server.
at first all were right but after 10 minutes we were not able to connect to server
without console.

We checked all possible option but failed.
suddenly, one of our system admin unpluged the network cable then plug.

after this all were 0k. we don't whats the problem? may be port hang.. or may be something else ....