Kinsta is blocking the connection
The request never reached the connector plugin. A security layer in front of the site answered instead, so Sentro received a challenge or block page rather than the JSON response it expects from /wp-json/crhub/v1/.
What the site owner can and cannot change
Kinsta's firewall and bot protection run on the platform edge and are managed by Kinsta, not from MyKinsta. There is no customer-side setting to exclude a path, so ask Kinsta support to allow requests to the connector path with the sentence below. If you also use your own Cloudflare account in front of the site, follow the Cloudflare guide as well.
Sentence you can send to support
Copy this to your host or firewall provider.
Our WordPress site is managed by Sentro. Requests to the REST path /wp-json/crhub/v1/ are being blocked by your security layer before they reach the site. All of these requests come from one fixed IP address, 185.166.188.64, and identify themselves with the user agent RootsWP/2.4.1 (+https://rootswp.com). Could you allow that IP address, or exclude the path /wp-json/crhub/v1/ from bot protection, firewall rules and rate limiting?
Our outbound IP address
Every request Sentro makes to your site leaves from one fixed IPv4 address: 185.166.188.64. Add that address to the allowlist of your firewall, security plugin or host and our calls to /wp-json/crhub/v1/ get through. You can send your host our IP page at https://rootswp.com/docs/ip.
We have not verified the current interface of this product, so this page describes the setting in general terms rather than naming menus that may have changed.