Switch to Settings tab and set payment threshold. For example, if your balance is 0.79 ETH. Then you can try typing 0.79.  It will require your rig's public ip address. For this purpose, you can retrive public ip by visiting https://www.whatismyip.com/ from the rig's browser.

If 0.79 does not work, you can try 0.75. These are the numbers but you will get the idea.

Good luck.