Hi,
I will check and fix 504 error on server with "ERR_HTTP2_SERVER_REFUSED_STREAM".I have extensive experience of Linux servers such as cPanel/WHM, Plesk, Virtualmin LAMP Stack, Tomcat, Mysql/Mairadb, Zimbra, Postfix mail server. And i have hands-on experience of data centers and cloud providers such AWS, GCP, DigitalOcean, Rackspace, Hostgator, Bluehost, Dreamhost.
Let's discuss.
Thank you