No downtime doesnt mean that the vhost answer to request. I'll try to make a network capture from my PC browser next time it happens, scripts took minutes to load on 2 differents ISP with fiber connections. Tell me if you need more informations.
Just how long it's all been happening, any relevant screenshots, whether you're using a VPN, etc. As I said though, nothing's changed recently and everything looks fine from the server end. No issues with the SSL, either.