I know there was a thread on this a couple of years ago but I cant find it. I few my drone yesterday and it worked fine with no limitation on the distance. Second flight and a new battery, I was limited to 500 meters. Beginner mode was off and so was max distance and max flight altitude.

Can anyone remind me of the fix for this?

You didn't leave any clues last time:
https://forum.dji.com/forum.php?mod=viewthread&tid=188266

Perhaps your flight data will have the key to the mystery.
Go to http://www.phantomhelp.com/LogViewer/Upload/
It has instructions to find the .txt file from your phone or tablet which you can upload to that site
Upload it and it gives you a summary of the flight data.
Post a link to that summary.

Or just post the .txt file

Hi there. Thank you for reaching out and we're sorry for the trouble that this has caused. Can you please confirm if you did receive an error message on the DJI Go app when you experience the said issue? In addition, kindly please try to fly the unit in a different location for us to check if the issue persists. Please keep us posted. Thank you.