Links from submenu on one page produce 404 error

I put your link:
https://www.elmersmfg.com/products/haul-master/haul-master-video.html#i1
in a redirect checker service:
https://www.internetofficer.com/seo-tool/redirect-check/
and it tells me the url has moved permanently and gives the new url as the non-working one.

Are you running any kind of redirect plugin? Some security or seo plugins can also setup redirects. If not, there may be something unwanted in your .htaccess file. Rename it to put it out of action, then reset permalinks in Settings. Resetting will create a fresh .htaccess.

Ultimately you may need to deactivate all plugins and delete .htaccess, then reactivate your plugins one-by-one to try to identify which one is causing the unwanted redirect.

Thanks for checking it out.

I do have a redirect plugin. I disabled it as you mentioned but then the site produced a white/blank page with the message “error” on it. I couldn’t get back into Admin. I just restored the database from a backup I had made just in case and had the site back running.

I’m using a plugin so I can have .html as link extension. I disabled this plugin, renamed the .htaccess and then reset the permalinks. So after this it worked as long as I didn’t use .html at the end of a link. But now links with .html extension didn’t work, giving me a 404 page.

I’ve changed this back as they were before since that way only one link gives me a 404 error. I just might remove the plugin which allows me to use .html, once I have more time, and then make sure to remove all .html extensions.

I’ll mark this as resolved.

Again, thanks for your help.