Apache .htaccess <IF> statement with multiple matches
Are you sure you did not make any syntax mistakes?
Usage of || is done this way and it works fine:
<If "%{HTTP_USER_AGENT} == 'Mozilla/5.0 (Windows NT 5.1; rv:7.0.1) Gecko/20100101 Firefox/7.0.1' || %{HTTP_USER_AGENT} == 'Mozilla/5.0 (Windows NT 6.1; WOW64)'">
Require all denied
</If>
Reference for expressions in Apache HTTP:
https://httpd.apache.org/docs/current/expr.html