Create new ftp user

useradd -m -d /home/sarah sarah
passwd sarah

Give password: 575757aA

usermod -g www-data sarah

Add user to vsftpd

cd /etc/vsftpd
nano sarah
local_root=/var/www/sarah/public_html
htpasswd -cd /etc/vsftpd/ftpd.passwd sarah

Will ask for password now

575757aA

Then edit user home directory (not sure if this is actually needed anymore)

usermod --home /var/www/sarah/public_html sarah

Check that user can write to directory

sudo chown -R sarah:www-data /var/www/sarah/public_html
chmod 775 /var/www/sarah/public_html
/etc/init.d/vsftpd restart

For changes to take effect restart apache

service apache2 restart

Try connecting to FTP using FTP user, password and port 21

Need port 21 because WordPress doesn’t allow changing of ports