MySQL: 'user'@'hostname' vs 'user'@'IPaddress'
I had this problem before, and after long investigation I found out sometimes MySQL can not resolve any issue related to DNS by default, so I did the following: edited hosts file ( can be found under Linux /etc/hosts, for Windows C:\Windows\System32\drivers\etc\hosts) and added ip and hostname for the client machine,in your example its 

10.11.12.13 foobarhost


then save and close ( note Windows will require reboot before taking any effect), you may need to add the following parameters --skip-name-resolve and\or --skip-host-cache .