I have just come across the issue. However I was previously using JetPack and had it connected with the self-hosted wordpress website. It was running flawlessly. JetPack Site Stats were also being updated which is the most frequent section I used to see after logging into /wp-admin.
But just recently when I tried to connect via WordPress App on Android, it denied access. Then I headed to PC and checked the XML-RPC file, it was there but I couldn’t access it via browser as it was returning 404 error. I was curious that how it could be possible as it was working before when I connected with JetPack.
At this point the JetPack services were still working on my self-hosted website. But as I had also activated the “Manage Site from www.remarpro.com”, I went over at www.remarpro.com to see what’s the status. That’s where the site was available but www.remarpro.com was having issues connecting with it.
[still JetPack services from the self-hosted website were working fine including photon, site stats, custom CSS, etc.]
Now I just wanted to check by reconnecting the JetPack from self-hosted website after disconnecting it. And that’s it. When I tried to reconnect with JetPack, my self-hosted website was no more accessible by JetPack with 404 error as well as the self-hosted website has now lost access to all of the JetPack features.
Assuming that my host suddenly blocked access to XML-RPC, I tried renaming the xmlrpc.php file and using a plugin as suggested here https://apps.wordpress.com/support/#faq-ios-11 but it didn’t work.
I also tried allowing xmlrpc.php in my .htaccess specifically but it also didn’t work.
Is there a way I do not require contacting host for this issue?