String Substring is not working - Error starting index can not be larger than the length

String Substring is not working - Error starting index can not be larger
than the length

The error keeps saying "startIndex cannot be larger than length of string.
Parameter name: startIndex"
IntializedPorts[i] = int.Parse(ports[i].ToString().Substring(105, 106));
//I tried this too
IntializedPorts[i] = int.Parse(ports[i].ToString().Substring(105, 1));
//The string I'm trying to substring, Im trying to get the number 7 at the
end of the ipaddress in the string
5b5bfdfe-6eb1-4b10-80af-cf4d9f1010fe3fc8ffa1-c16b-4d7b-9e55-1e88dfe15277FastTrackVirusSoftware192.168.6.17TCP/IPYESReady8/4/2013
1:07:43 PM9/1/2013 1:07:43 PM