I'm working on a site that was heavily impacted by the September core update. You can see in the attached image the overall downturn in organic in 2019 with a larger hit in September bringing Google Organic traffic down around 50%. There are many concerning incoming links from 50-100 obviously spammy porn-related websites to just plain old unnatural links. There was no effort to purchase any links so it's unclear how these are created. There are also 1,000s of incoming external links (most without no-follow and similar/same anchor text) from yellowpages.com. I'm trying to get this fixed with them and have added it to the disavow in the meantime. I'm focusing on internal links as well with a more specific question: If I have a sitewide header on a blog located at blog.domain.com that has links to various sections on domain.com without no-follow tags, is this a possible source of the traffic drops and algorithm impact? The header with these links is on every page of the blog on the previously mentioned subdomain. **More generally, any advice as to how to turn this around? ** The website is in the travel vertical. 90BJKyc