Did you touch base with the Yoast support people? Did they send you here? Did they then tell you what to tell us?
You didn’t give us a URL so I couldn’t even take a look. I can often look and see what the problem is if given half a chance.
]]>That Nginx proxy out front of your website is running a vulnerable older version also.
What PHP version are you running? I can’t see that as that proxy box is blocking my view.
Your Facebook link points at your profile there… Wouldn’t a Facebook ‘Page’ be a better bet for your business?
Your theme is a commercial theme so when you have issues with your site your best course would be to temporarily install a default WordPress theme like Twenty Seventeen and see if the problem goes away.
You could then determine if the Theme caused the problem or not and reach out to the theme author for help or switch out to a different theme as appropriate.
You say Yoast doesn’t work properly but you are running the free Yoast version so you’ll need to DIY your own support or wait for them to help you. That’s not a big issue anyway as Yoast isn’t ‘mission-critical’.
My advice would be to step up to a newer PHP version like 7.3.X and update your WordPress to 4.9.10 at least if you don’t want to run 5.2.3 or whatever is the latest greatest 5.X version.
I’d be asking my web host to explain why the proxy is reporting as vulnerable.
I’d be off that DNS server ASAP as I see issues there but I’m right particular about DNS. Cloudflare might be a good option for you.
It’s not really fair to blame WordPress for your problems when you haven’t supplied the environment where WordPress can flourish.
Same with Yoast. I think Yoast might even be more demanding of the PHP version and resources needed and their documentation probably tells you that.
]]>