diff --git a/backend/internal/certificate.js b/backend/internal/certificate.js
index d3bc8ff7..6161ce2d 100644
--- a/backend/internal/certificate.js
+++ b/backend/internal/certificate.js
@@ -1180,10 +1180,13 @@ const internalCertificate = {
 			} else if (`${result.responsecode}` === '200' && result.htmlresponse === 'Success') {
 				// Server exists and has responded with the correct data
 				return 'ok';
+			} else if (`${result.responsecode}` === '200') {
+				// Server exists and has responded with the correct data
+				return 'wrong-data';
 			} else if (`${result.responsecode}` === '404') {
 				// Server exists but responded with a 404
 				return '404';
-			} else if (`${result.responsecode}` === '0' || result.reason.toLowerCase() === 'host unavailable') {
+			} else if (`${result.responsecode}` === '0' || (typeof result.reason === 'string' && result.reason.toLowerCase() === 'host unavailable')) {
 				// Server does not exist at domain
 				return 'no-host';
 			} else {
diff --git a/frontend/js/app/nginx/certificates/test.ejs b/frontend/js/app/nginx/certificates/test.ejs
index c941a779..6661f625 100644
--- a/frontend/js/app/nginx/certificates/test.ejs
+++ b/frontend/js/app/nginx/certificates/test.ejs
@@ -7,7 +7,7 @@
             <%= i18n('str', 'please-wait') %>
         </div>
         <div class="alert alert-danger error" role="alert"></div>
-        <div class="alert alert-danger success" role="alert"></div>
+        <div class="alert alert-success success" role="alert"></div>
     </div>
     <div class="modal-footer">
         <button type="button" class="btn btn-secondary cancel" disabled><%- i18n('str', 'close') %></button>
diff --git a/frontend/js/app/nginx/certificates/test.js b/frontend/js/app/nginx/certificates/test.js
index b29fd5eb..0886d26f 100644
--- a/frontend/js/app/nginx/certificates/test.js
+++ b/frontend/js/app/nginx/certificates/test.js
@@ -45,6 +45,8 @@ module.exports = Mn.View.extend({
 							text += `<p><strong>${domain}:</strong> ${App.i18n('certificates', 'reachability-failed-to-check')}</p>`;
 						} else if (status === '404') {
 							text += `<p><strong>${domain}:</strong> ${App.i18n('certificates', 'reachability-404')}</p>`;
+						} else if (status === 'wrong-data') {
+							text += `<p><strong>${domain}:</strong> ${App.i18n('certificates', 'reachability-wrong-data')}</p>`;
 						} else if (status.startsWith('other:')) {
 							const code = status.substring(6);
 							text      += `<p><strong>${domain}:</strong> ${App.i18n('certificates', 'reachability-other', {code})}</p>`;
diff --git a/frontend/js/i18n/messages.json b/frontend/js/i18n/messages.json
index f231de52..02f2abef 100644
--- a/frontend/js/i18n/messages.json
+++ b/frontend/js/i18n/messages.json
@@ -196,6 +196,7 @@
       "reachability-ok": "Your server is reachable and creating certificates should be possible.",
       "reachability-404": "There is a server found at this domain but it does not seem to be Nginx Proxy Manager. Please make sure your domain points to the IP where your NPM instance is running.",
       "reachability-not-resolved": "There is no server available at this domain. Please make sure your domain exists and points to the IP where your NPM instance is running and if necessary port 80 is forwarded in your router.",
+      "reachability-wrong-data": "There is a server found at this domain but it returned an unexpected data. Is it the NPM server? Please make sure your domain points to the IP where your NPM instance is running.",
       "reachability-other": "There is a server found at this domain but it returned an unexpected status code {code}. Is it the NPM server? Please make sure your domain points to the IP where your NPM instance is running.",
       "download": "Download",
       "renew-title": "Renew Let'sEncrypt Certificate"