I am facing with this problem today, while trying to connect to a remote mysql on a network. Framework used Laravel 5.3. I have configured properly the .env file with excact credentials. Yesterday was working fine.
It seems, that you have a network problem. Usually on a network ip changes from time to time. Please check the
IP of the remote pc or computer on the network. If
IP has changed, update again the .env file. Good luck.