You are always mining at the current network diff when solo mining so any "shares" submitted are effectively considered the network diff so any rejects will be shown to be at the network diff as well. "Diff shares" is number of shares (in this case 1) multiplied by the difficulty you're mining at (in this case network diff). You definitely didn't even get close to the network diff but the software decided to try submitting a share anyway and it got rejected. You can see what your best share was, it was only 26,500 when network diff is 708 billion.