my site health option says:
Unable to detect page caching due to possible loopback request problem. Please verify that the loopback request test is passing. Error: Service Unavailable (Code: http_503)
The AMP plugin performs at its best when page caching is enabled. This is because the additional optimizations performed require additional server processing time, and page caching ensures that responses are served quickly.
Page caching is detected by looking for an active page caching plugin as well as making three requests to the homepage and looking for one or more of the following HTTP client caching response headers: cache-control, expires, age, last-modified, etag, x-cache, x-proxy-cache, cf-cache-status, x-kinsta-cache, x-cache-enabled, x-cache-disabled, cf-apo-via, x-srcache-store-status, x-srcache-fetch-status, cf-edge-cache.
