Hey Tanya,
2 main issues is the amount of data is not enough, especially to generate 300 trades on h1.
also some OOS would be a good idea and also Monte Carlo for robustness.
what courses have you been through?
also what symbols are you planning to trade etc?
Did you resolve the issue of low generations first with a single EA browser as it seemed to be a window becoming inactive issue?
Your 6 core vps should be able to handle about 4-6 browsers comfortably depending on how many mt4 terminals you are also running but make sure to check your processor utilization also.