diff --git a/src/cloudron.js b/src/cloudron.js
index a80e2c1a1..9f9abfb46 100644
--- a/src/cloudron.js
+++ b/src/cloudron.js
@@ -8,6 +8,7 @@ exports = module.exports = {
     activate: activate,
     getConfig: getConfig,
     getStatus: getStatus,
+    dnsSetup: dnsSetup,
 
     sendHeartbeat: sendHeartbeat,
     sendAliveStatus: sendAliveStatus,
@@ -113,6 +114,7 @@ CloudronError.BAD_FIELD = 'Field error';
 CloudronError.INTERNAL_ERROR = 'Internal Error';
 CloudronError.EXTERNAL_ERROR = 'External Error';
 CloudronError.ALREADY_PROVISIONED = 'Already Provisioned';
+CloudronError.ALREADY_SETUP = 'Already Setup';
 CloudronError.BAD_STATE = 'Bad state';
 CloudronError.ALREADY_UPTODATE = 'No Update Available';
 CloudronError.NOT_FOUND = 'Not found';
@@ -208,6 +210,23 @@ function syncConfigState(callback) {
     });
 }
 
+function dnsSetup(dnsConfig, domain, callback) {
+    assert.strictEqual(typeof dnsConfig, 'object');
+    assert.strictEqual(typeof domain, 'string');
+    assert.strictEqual(typeof callback, 'function');
+
+    if (config.fqdn()) return callback(new CloudronError(CloudronError.ALREADY_SETUP));
+
+    config.set('fqdn', domain); // set fqdn only after dns config is valid, otherwise cannot re-setup if we failed
+
+    settings.setDnsConfig(dnsConfig, domain, function (error) {
+        if (error && error.reason === SettingsError.BAD_FIELD) return callback(new CloudronError(CloudronError.BAD_FIELD, error.message));
+        if (error) return callback(new CloudronError(CloudronError.INTERNAL_ERROR, error));
+
+        callback();
+    });
+}
+
 function configureAdmin(callback) {
     callback = callback || NOOP_CALLBACK;
 
diff --git a/src/routes/cloudron.js b/src/routes/cloudron.js
index 72a8b0bd9..10b6de10d 100644
--- a/src/routes/cloudron.js
+++ b/src/routes/cloudron.js
@@ -87,13 +87,11 @@ function dnsSetup(req, res, next) {
     assert.strictEqual(typeof req.body, 'object');
 
     if (typeof req.body.provider !== 'string') return next(new HttpError(400, 'provider is required'));
-    if (config.fqdn()) return next(new HttpError(409, 'Already setup'));
     if (typeof req.body.domain !== 'string' || !req.body.domain) return next(new HttpError(400, 'domain is required'));
 
-    config.set('fqdn', req.body.domain);
-
-    settings.setDnsConfig(req.body, req.body.domain, function (error) {
-        if (error && error.reason === SettingsError.BAD_FIELD) return next(new HttpError(400, error.message));
+    cloudron.dnsSetup(req.body, req.body.domain, function (error) {
+        if (error && error.reason === CloudronError.ALREADY_SETUP) return next(new HttpError(409, error.message));
+        if (error && error.reason === CloudronError.BAD_FIELD) return next(new HttpError(400, error.message));
         if (error) return next(new HttpError(500, error));
 
         next(new HttpSuccess(200));