How to do linking between subdomains?

Question

Search Engine Optimization

Hello. Created several subdomains in addition to the blog (forum and something else). I want to indicate links to other subdomains of the site in the footer of each. This can be done with dofollow links, or better nofollow, so as not to harm SEO.

Because once, out of ignorance, I added a link to another resource in the menu of one of my sites. As a result, the first one where I added a through link fell to the bottom of the search, after which I brought him to his senses for a long and tedious time.

Will this happen with subdomains?

Answer 1

That's not why he fell.