How to stop server overload, Apache, MySQL and Php config

I have set up a basic 1GB server running Ubuntu and Apache2.4.46, PHP7.4.16 MySQL 8.0.27. I am running one Wordpress installation on it.

I seem to be able to overload and crash the server by repeatedly refreshing pages (holding down command and reload). I made the time that this takes to happen a lot longer by making some changes to configs. Whilst this is an edge case situation, I would like to know if there is a way to make sure my server can not get overloaded from multiple requests.

Are there other settings for Apache, MySQL or PHP (or other) I could change to help with load.

Many thanks in advance.

**PHP set up: PHP Memory Limit 256 MB PHP Post Max Size 256M PHP Time Limit 300 PHP Max Input Vars 5000 Max Upload Size 128 MB

**MySQL key_buffer_size = 128M max_allowed_packet = 16M thread_stack = 192K thread_cache_size = 8 myisam-recover-options = BACKUP max_connections = 20 max_binlog_size = 100M interactive_timeout = 30 wait_timeout = 30 skip-name-resolve I have run mysql tuner and the only recommendation is: innodb_log_file_size should be (=16M) if possible, so InnoDB total log files size equals to 25% of buffer pool size.

**Apache Timeout 30 KeepAlive On MaxKeepAliveRequests 10 KeepAliveTimeout 1