This scenario can originate from plugins modifying your .htaccess documents to include or modify rules, or from an outdated WordPress MU configuration not current considering that Multisite was added. You can know everything about your server, enhance selected settings and down load a TXT report of these values. this is https://australianewsnetwork.com/wps-office%e4%b8%ad%e6%96%87%e7%89%88%e4%b8%8b%e8%bd%bd%ef%bc%9a%e9%ab%98%e6%95%88%e5%8a%9e%e5%85%ac%e7%9a%84%e9%a6%96%e9%80%89/