SiteGround 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
SiteGround's Anti-Bot AI runs at server level, in front of your website. It is not a WordPress plugin and it is not a switch in Site Tools: you cannot turn it off yourself, and there is no per-path exclusion exposed to customers. The Blocked Traffic list in Site Tools is a different feature — it is for IP addresses you block yourself, and adding an address there does not stop the Anti-Bot AI from challenging that address. This is worth knowing before you spend time on it, because it is the first thing most people try. The only resolution is a support request to SiteGround, asking them to disable the Anti-Bot AI for this site or to exclude the path /wp-json/ from it. The same issue affects other WordPress management platforms, such as MainWP.
One extra argument for your ticket: the captcha challenge page is served with a noindex header. A search engine crawler that gets challenged therefore receives noindex instead of your page, which can cause pages to drop out of Google's index. That is a reason to fix this even apart from site management.
Support ticket to send
Fill in your domain and send this text to support. It is in English on purpose, so it can be forwarded as is.
Hello, requests to our site's REST API are being intercepted by the SG Anti-Bot AI. A request to https://your-domain.com/wp-json/crhub/v1/health is redirected to /.well-known/sgcaptcha/ instead of reaching WordPress, so our site management tool cannot connect. All these requests come from one fixed IP address, 185.166.188.64, and use the user agent Sentro (+https://rootswp.com). Could you either allow that IP address for this site, or disable the Anti-Bot AI for the site, or exclude the path /wp-json/ from it? Allowing the single IP address is the smallest change and keeps the protection in place for everyone else. Please also note the captcha challenge page is served with a noindex header, which risks our pages being dropped from search engine indexes.
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.
The steps on this page were checked against the vendor documentation linked below.