Hi there @DaniGAN,

It seems like an issue with Apache or PHP, I would recommend following the steps from this answer here on how to troubleshoot common Apache problems:

https://www.digitalocean.com/community/questions/how-to-troubleshoot-common-apache-issues-on-linux-server

Feel free to share the output of the commands here so that I could advise you further.

I would recommend starting with your Apache error log, you can check the last 100 entries with this command here:

tail -100 /var/log/apache2/error.log

This would give you more information about the actual problem.

Regards,
Bobby