Custom menu links not working in blog post

Hi there,

For the front page of my website I have successfully set up custom links for my menu at the top of the page, however, when I create a new blog post that same menu will appear on the post page and the links do not work, they will not take me back to the main page. I always get the following error;

“Your connection is not private
Attackers might be trying to steal your information from (for example, passwords, messages, or credit cards). NET::ERR_CERT_COMMON_NAME_INVALID
Automatically send some system information and page content to Google to help detect dangerous apps and sites. Privacy policy”

How can I get these links to work? Do I have to create a new menu for the blog post??