Let’s see why the connection between the LR plugin and the WP plugin is not working.
Before the WP/LR Sync for LR 2.6.0, the plugin was always using XML/RPC, which was not playing well with many hosting services (because of historical security issues in the protocol, even though it has been fixed for a long time now). I therefore recommend you to switch to the latest version of the LR plugin and change the Protocol setting of your Publish Service to REST. Try again, and go to 2 if it is still not working.
If you are really willing to use XML/RPC, have a look here.
Check if /wp-json is available on your install. For example, on my haikyo.org website, this URL is http://haikyo.org/wp-json. Understanding it is not important, but make sure that the “wplr” string is present somewhere in this. If you can’t find “wplr”, then the WordPress API is disabled on your install, that will not work.
The WordPress API needs the .htaccess to work. Sometimes, WordPress doesn’t do it magically and you need to trigger it. Check your Permalink Settings (/wp-admin/options-permalink.php), check Post Name (as long as it is not Plain), Save Changes. Do what described in the first paragraph again. Does it work better? It is a good practice to use permalinks. If you don’t want to use those permalinks for some reason, check this: StackOverflow.
Sounds like not a very clever question, but sometimes that might be that the plugin is disabled 🙂 Can you check your Plugins page in WordPress? If not, enable it and try everything again. Also, there are plugins that can disable other plugins or their functions. Please make sure you try to disable all the plugins and test WP/LR Sync alone (such plugin as Plugin Organizer for example can do that).
Make sure the WordPress URL you set works. Also, try it with http or https. It’s often an issue.
Make sure that the plugin and your website works normally. The plugin might not work properly if:
Once you found why it is not working, you need to find an alternative to do what you need. If it is a security plugin of else, you need to check with them how to keep have the WP REST API enabled.
You have to be aware that if any other plugin fails or generate an error during the syncing process, WP/LR Sync will be stopped. Therefore, you need to check your PHP Error Logs to make sure nothing happens during the WP/LR Sync process. Check it before using WP/LR Sync, perform an action (or the specific action which failed) and check it again. Did something happen in between?
Disable all the plugins (except WP/LR Sync), disable all the extensions you have chosen for WP/LR Sync, try again. Does it work?
Your PHP error logs are made accessible by your hosting service, if you don’t know where they are, the best is to ask them. You can also try to use such a plugin as Error Log Monitor (but they don’t always detect the error file). If you are willing to learn more about checking errors by yourself, check this: Monitor PHP Errors. Be careful, the PHP Error Logs is not the Access Error Logs, they are two different things.
Alternatively, you can also have a look at your WPLRSync.log located in your Documents folder, it sometimes contain interesting information.
Nothing worked? Make sure you tried everything above because that covers 99.8% of the issues. I will not be able to give you more advices that what is on this page so the only way is that you give me access to your WordPress. Create credentials with admin access for me, make a backup on your install (just in case) and contact me.