"Set innodb_buffer_pool_size to 80% of RAM"

"Set innodb_buffer_pool_size to 80% of RAM"
That rule is for dedicated DB servers. On a $5 LEMP box where PHP-FPM, nginx AND MySQL share 2GB, 80% means instant OOM.
Reality on a shared box: size it to your actual data, not your RAM. Check it:
SELECT table_schema, SUM(data_length+index_length)/1024/1024 FROM information_schema.tables GROUP BY 1;
If your DB is 300MB, a 512MB pool caches everything. Save the rest for everything else.
Try it tonight.