Ethernet sheild stops connecting after an extended period

When I strip the Ethercheck void back to just printing the client without the strings it works until my computer sleeps (at five hours). I think this means it is the strings causing the problem.

I currently use the .startsWith to find out if the tweet starts with the same words as makeCoffee in order to recognise a tweeted command. I am told by the console that I cannot use .startsWith with Char. I have researched a function called memcmp(); Is this what I have to use to create a comparison between two chars?

Also if I cannot say

   currentLine += inChar;

When currentLine is a char, not a string.. how do I complete the function with currentLine as a char?