Redirect from mysite.ru to www.mysite.ru doesn't work through 301 via .htaccess?

Question

htaccess

Good afternoon, I ask you to tell me,
the current contents of the .htaccess file, the commented lines are attempts to write a redirect differently, which also failed.
I ask you to clarify in my head, otherwise something is completely confused.
The IP registrar has the same address for both domains (www.mysite.ru; mysite.ru).
Options All -Indexes
ErrorDocument 403 /error/403.html
ErrorDocument 404 /error/404.html
Options +FollowSymLinks
RewriteEngine On
RewriteCond %{HTTP_HOST} ^mysite.ru
RewriteRule (.*) www.mysite.ru/$1 [R=301 ,L]
#RewriteCond %{HTTP_HOST} ^mysite.ru$ [NC]
#RewriteRule ^(.*)$ www.mysite.ru/$1 [R=301,L]
#RewriteCond %{HTTP_HOST} ^([^www].*)$
#RewriteRule ^(.*)$ http://www.%1/$1 [L,R=301]

Answer 1

I'll answer myself.
you need to check
/etc/apache2/apache2.conf
for the presence of AllowOveride All in it,
check if mod_rewrite is enabled in your Apache,
sudo a2enmod rewrite
if not, then you need to restart the Apache service after that,
then add the following entries to the .htaccess file
RewriteEngine On
RewriteBase /
RewriteCond %{HTTP_HOST} ^mysite.ru [NC]
RewriteRule ^(.*)$ www.mysite.ru/$1 [L,R=301]