Hi I am running a local server running Ubunto 16.04LTS with a stock LAMP
install that runs  stock Apache. 

I have an install of WordPress under
/var/www/vhost/{vhost-name}/public_html 

Here is my problem. 

I can either FTP or WordPress can edit / remove file.  I cannot do both.
 Not sure why. 

To allow WordPress to modify files I must:  (I cannot SFTP) 

 	* chown -R {my-user-name}:www-data www/
 	* chmod -R 755 www/

To allow me to SFTP I must change the file ownership:  (WordPress cannot
modify files) 

 	* chown -R {my-user-name}:www-data www/

I would like to be able to FTP and allow WordPress to modify files. 

Any help much appreciated. 

Thanks!!