You may get some errors on a PORT.
1) Check db is ok –login , do some queries, show processlist a few times to see that queries are being processed. Check my.cnf to see setting for max connections.
2) Check error log
3) Do netstat –n | more …will see WAIT status …these cant connect on the port. Mostly due to resource limitation on the server.
4) Can clear out old/stale connections that may still be hogging resource , flush hosts;