videoanimate

Thank you, this narrowed it down perfectly.

CURL RESULT — registration works correctly:
I ran the /register probe (via a JSON file to avoid Windows quoting issues) and
got a proper rmcp_ client back:

{“client_id”:”rmcp_66dd90d85f0f9ce769428c378ed9478e”,”client_name”:”diagnostic”,
“redirect_uris”:[“https://claude.ai/api/mcp/auth_callback”%5D,
“grant_types”:[“authorization_code”],”token_endpoint_auth_method”:”none”,
“response_types”:[“code”],…}

So Royal MCP is handling registration correctly, and there is no second OAuth
plugin intercepting. That points to cause #1 (the static OAuth Client ID override).

THE ACTUAL BLOCKER — the static field won’t clear:
This is the key issue. In Settings -> Advanced, the OAuth Client ID field
contains the wp_HQx4Tj0l6Hr8JMx0cvs2Wl5v value. But I CANNOT clear it:

• I click Clear / delete it manually / Save Changes
• I run Reset OAuth State from Troubleshooting
• …and the wp_… value always comes back to the field after saving/reloading.

So the static override keeps getting restored, which is why /authorize keeps
looking up the wp_ id and failing with “Unknown client_id”.

Questions:

1. Why would the OAuth Client ID field not clear / keep reverting after Save and
   after Reset OAuth State? Is this value possibly cached (I do have caching on
   the site) or read from somewhere other than the DB (e.g. a constant in
   wp-config.php or an mu-plugin)?
2. Where exactly does Royal MCP read this static OAuth Client ID from, so I can
   remove it at the source if the UI can’t?
3. Is there a way to fully wipe the OAuth state (including any stored static
   client) via wp-cli or by deleting a specific option row?

Also noting your connectivity flag: you mentioned the TCP handshake to my site
was refused from your diagnostic host. I’m checking with my hosting provider
about any IP/geo restriction on port 443, since that could also affect Anthropic’s
rotating OAuth IPs.

Thanks again for the clear guidance.