Enable to connect with FTP after right changes in Ubuntu

Question

I created a user like this on my server:

sudo adduser [username]
echo [username] >> /etc/vsftpd.userlist
usermod --home /var/www/[username]/public_html [username]

I was able to connect to the directory with any FTP client but the user has only the read rights.

So I changed this and updated the right like this:

sudo chown -R [username] /var/www/[username]/public_html
sudo chmod -R 755 /var/www/[username]/public_html

Unfortunately, after this, I'm enable to connect with FTP to the directory anymore.

The right of the directory changed to:

drwxr-xr-x  5 [username] root 4096 Mar  5 19:57 public_html/

What I'm missing here please ?

Thanks.