If you see the error message 'MySQL Server has gone away', it is possible that your script is not fully optimized and makes too many connections to the database. It may also happen due to excessive amounts of traffic.
Another probable cause for this issue may be heavy or slow MySQL queries.
In either case, in order to solve this problem, you should check if your database is well optimized and has indexes set up correctly. If you are using a 3rd party script, you should definitely try contacting script developers and ask them for assistance on this matter!