diff --git a/application/src/test/java/org/thingsboard/server/controller/DeviceConnectivityControllerTest.java b/application/src/test/java/org/thingsboard/server/controller/DeviceConnectivityControllerTest.java
index 383a050bb2..525e18240d 100644
--- a/application/src/test/java/org/thingsboard/server/controller/DeviceConnectivityControllerTest.java
+++ b/application/src/test/java/org/thingsboard/server/controller/DeviceConnectivityControllerTest.java
@@ -396,4 +396,10 @@ public class DeviceConnectivityControllerTest extends AbstractControllerTest {
     public void testDownloadMqttCertWithoutCertFile() throws Exception {
         doGet("/api/device-connectivity/mqtts/certificate/download").andExpect(status().isNotFound());
     }
+
+    @Test
+    @DirtiesContext
+    public void testDownloadCertWithUnknownProtocol() throws Exception {
+        doGet("/api/device-connectivity/unknownProtocol/certificate/download").andExpect(status().isNotFound());
+    }
 }
diff --git a/dao/src/main/java/org/thingsboard/server/dao/device/DeviceConnectivityConfiguration.java b/dao/src/main/java/org/thingsboard/server/dao/device/DeviceConnectivityConfiguration.java
index 99a4014f48..227b531be0 100644
--- a/dao/src/main/java/org/thingsboard/server/dao/device/DeviceConnectivityConfiguration.java
+++ b/dao/src/main/java/org/thingsboard/server/dao/device/DeviceConnectivityConfiguration.java
@@ -28,6 +28,10 @@ import java.util.Map;
 public class DeviceConnectivityConfiguration {
     private Map<String, DeviceConnectivityInfo> connectivity = new HashMap<>();
 
+    public DeviceConnectivityInfo getConnectivity(String protocol) {
+        return connectivity.get(protocol);
+    }
+
     public boolean isEnabled(String protocol) {
         var info = connectivity.get(protocol);
         return info != null && info.isEnabled();
diff --git a/dao/src/main/java/org/thingsboard/server/dao/device/DeviceConnectivityServiceImpl.java b/dao/src/main/java/org/thingsboard/server/dao/device/DeviceConnectivityServiceImpl.java
index 995e3798b0..b30ae40808 100644
--- a/dao/src/main/java/org/thingsboard/server/dao/device/DeviceConnectivityServiceImpl.java
+++ b/dao/src/main/java/org/thingsboard/server/dao/device/DeviceConnectivityServiceImpl.java
@@ -81,7 +81,7 @@ public class DeviceConnectivityServiceImpl implements DeviceConnectivityService
 
     @PostConstruct
     private void init() {
-        DeviceConnectivityInfo mqtts = deviceConnectivityConfiguration.getConnectivity().get(MQTTS);
+        DeviceConnectivityInfo mqtts = deviceConnectivityConfiguration.getConnectivity(MQTTS);
         if (mqtts != null && mqtts.isEnabled()) {
             String certFilePath = mqtts.getPemCertFile();
             if (StringUtils.isBlank(certFilePath) || !ResourceUtils.resourceExists(this, certFilePath)) {
@@ -89,7 +89,6 @@ public class DeviceConnectivityServiceImpl implements DeviceConnectivityService
                 log.error("MQTTS is enabled but cert {}!", error);
             }
         }
-
     }
 
     @Override
@@ -140,9 +139,12 @@ public class DeviceConnectivityServiceImpl implements DeviceConnectivityService
     @Override
     public Resource getPemCertFile(String protocol) {
         return certs.computeIfAbsent(protocol, key -> {
-            String certFilePath = deviceConnectivityConfiguration.getConnectivity()
-                    .get(protocol)
-                    .getPemCertFile();
+            DeviceConnectivityInfo connectivity = deviceConnectivityConfiguration.getConnectivity(protocol);
+            if (connectivity == null) {
+                log.warn("Unknown connectivity protocol: {}", protocol);
+                return null;
+            }
+            String certFilePath = connectivity.getPemCertFile();
             if (StringUtils.isNotBlank(certFilePath) && ResourceUtils.resourceExists(this, certFilePath)) {
                 try {
                     return getCert(certFilePath);
@@ -195,7 +197,7 @@ public class DeviceConnectivityServiceImpl implements DeviceConnectivityService
     }
 
     private String getHttpPublishCommand(String protocol, String baseUrl, DeviceCredentials deviceCredentials) throws URISyntaxException {
-        DeviceConnectivityInfo properties = deviceConnectivityConfiguration.getConnectivity().get(protocol);
+        DeviceConnectivityInfo properties = deviceConnectivityConfiguration.getConnectivity(protocol);
         if (properties == null || !properties.isEnabled() ||
                 deviceCredentials.getCredentialsType() != DeviceCredentialsType.ACCESS_TOKEN) {
             return null;
@@ -246,14 +248,14 @@ public class DeviceConnectivityServiceImpl implements DeviceConnectivityService
     }
 
     private String getMqttPublishCommand(String baseUrl, String deviceTelemetryTopic, DeviceCredentials deviceCredentials) throws URISyntaxException {
-        DeviceConnectivityInfo properties = deviceConnectivityConfiguration.getConnectivity().get(MQTT);
+        DeviceConnectivityInfo properties = deviceConnectivityConfiguration.getConnectivity(MQTT);
         String mqttHost = getHost(baseUrl, properties);
         String mqttPort = properties.getPort().isEmpty() ? null : properties.getPort();
         return DeviceConnectivityUtil.getMqttPublishCommand(MQTT, mqttHost, mqttPort, deviceTelemetryTopic, deviceCredentials);
     }
 
     private List<String> getMqttsPublishCommand(String baseUrl, String deviceTelemetryTopic, DeviceCredentials deviceCredentials) throws URISyntaxException {
-        DeviceConnectivityInfo properties = deviceConnectivityConfiguration.getConnectivity().get(MQTTS);
+        DeviceConnectivityInfo properties = deviceConnectivityConfiguration.getConnectivity(MQTTS);
         String mqttHost = getHost(baseUrl, properties);
         String mqttPort = properties.getPort().isEmpty() ? null : properties.getPort();
         String pubCommand = DeviceConnectivityUtil.getMqttPublishCommand(MQTTS, mqttHost, mqttPort, deviceTelemetryTopic, deviceCredentials);
@@ -268,7 +270,7 @@ public class DeviceConnectivityServiceImpl implements DeviceConnectivityService
     }
 
     private String getDockerMqttPublishCommand(String protocol, String baseUrl, String deviceTelemetryTopic, DeviceCredentials deviceCredentials) throws URISyntaxException {
-        DeviceConnectivityInfo properties = deviceConnectivityConfiguration.getConnectivity().get(protocol);
+        DeviceConnectivityInfo properties = deviceConnectivityConfiguration.getConnectivity(protocol);
         String mqttHost = getHost(baseUrl, properties);
         String mqttPort = properties.getPort().isEmpty() ? null : properties.getPort();
         return DeviceConnectivityUtil.getDockerMqttPublishCommand(protocol, baseUrl, mqttHost, mqttPort, deviceTelemetryTopic, deviceCredentials);
@@ -308,14 +310,14 @@ public class DeviceConnectivityServiceImpl implements DeviceConnectivityService
     }
 
     private String getCoapPublishCommand(String protocol, String baseUrl, DeviceCredentials deviceCredentials) throws URISyntaxException {
-        DeviceConnectivityInfo properties = deviceConnectivityConfiguration.getConnectivity().get(protocol);
+        DeviceConnectivityInfo properties = deviceConnectivityConfiguration.getConnectivity(protocol);
         String hostName = getHost(baseUrl, properties);
         String port = properties.getPort().isEmpty() ? "" : ":" + properties.getPort();
         return DeviceConnectivityUtil.getCoapPublishCommand(protocol, hostName, port, deviceCredentials);
     }
 
     private String getDockerCoapPublishCommand(String protocol, String baseUrl, DeviceCredentials deviceCredentials) throws URISyntaxException {
-        DeviceConnectivityInfo properties = deviceConnectivityConfiguration.getConnectivity().get(protocol);
+        DeviceConnectivityInfo properties = deviceConnectivityConfiguration.getConnectivity(protocol);
         String host = getHost(baseUrl, properties);
         String port = properties.getPort().isEmpty() ? "" : ":" + properties.getPort();
         return DeviceConnectivityUtil.getDockerCoapPublishCommand(protocol, host, port, deviceCredentials);