diff --git a/application/src/main/java/org/thingsboard/server/service/subscription/DefaultTbEntityDataSubscriptionService.java b/application/src/main/java/org/thingsboard/server/service/subscription/DefaultTbEntityDataSubscriptionService.java
index 632ea44940..019b6eb5e8 100644
--- a/application/src/main/java/org/thingsboard/server/service/subscription/DefaultTbEntityDataSubscriptionService.java
+++ b/application/src/main/java/org/thingsboard/server/service/subscription/DefaultTbEntityDataSubscriptionService.java
@@ -94,7 +94,7 @@ import java.util.stream.Collectors;
 public class DefaultTbEntityDataSubscriptionService implements TbEntityDataSubscriptionService {
 
     private static final int DEFAULT_LIMIT = 100;
-    private final Map<String, Map<Integer, TbAbstractSubCtx>> subscriptionsBySessionId = new ConcurrentHashMap<>();
+    private final ConcurrentMap<String, ConcurrentMap<Integer, TbAbstractSubCtx>> subscriptionsBySessionId = new ConcurrentHashMap<>();
 
     @Autowired
     @Lazy
@@ -495,7 +495,7 @@ public class DefaultTbEntityDataSubscriptionService implements TbEntityDataSubsc
     }
 
     private TbEntityDataSubCtx createSubCtx(WebSocketSessionRef sessionRef, EntityDataCmd cmd) {
-        Map<Integer, TbAbstractSubCtx> sessionSubs = subscriptionsBySessionId.computeIfAbsent(sessionRef.getSessionId(), k -> new HashMap<>());
+        Map<Integer, TbAbstractSubCtx> sessionSubs = subscriptionsBySessionId.computeIfAbsent(sessionRef.getSessionId(), k -> new ConcurrentHashMap<>());
         TbEntityDataSubCtx ctx = new TbEntityDataSubCtx(serviceId, wsService, entityService, localSubscriptionService,
                 attributesService, stats, sessionRef, cmd.getCmdId(), maxEntitiesPerDataSubscription);
         if (cmd.getQuery() != null) {
@@ -506,7 +506,7 @@ public class DefaultTbEntityDataSubscriptionService implements TbEntityDataSubsc
     }
 
     private TbEntityCountSubCtx createSubCtx(WebSocketSessionRef sessionRef, EntityCountCmd cmd) {
-        Map<Integer, TbAbstractSubCtx> sessionSubs = subscriptionsBySessionId.computeIfAbsent(sessionRef.getSessionId(), k -> new HashMap<>());
+        Map<Integer, TbAbstractSubCtx> sessionSubs = subscriptionsBySessionId.computeIfAbsent(sessionRef.getSessionId(), k -> new ConcurrentHashMap<>());
         TbEntityCountSubCtx ctx = new TbEntityCountSubCtx(serviceId, wsService, entityService, localSubscriptionService,
                 attributesService, stats, sessionRef, cmd.getCmdId());
         if (cmd.getQuery() != null) {
@@ -518,7 +518,7 @@ public class DefaultTbEntityDataSubscriptionService implements TbEntityDataSubsc
 
 
     private TbAlarmDataSubCtx createSubCtx(WebSocketSessionRef sessionRef, AlarmDataCmd cmd) {
-        Map<Integer, TbAbstractSubCtx> sessionSubs = subscriptionsBySessionId.computeIfAbsent(sessionRef.getSessionId(), k -> new HashMap<>());
+        Map<Integer, TbAbstractSubCtx> sessionSubs = subscriptionsBySessionId.computeIfAbsent(sessionRef.getSessionId(), k -> new ConcurrentHashMap<>());
         TbAlarmDataSubCtx ctx = new TbAlarmDataSubCtx(serviceId, wsService, entityService, localSubscriptionService,
                 attributesService, stats, alarmService, sessionRef, cmd.getCmdId(), maxEntitiesPerAlarmSubscription,
                 maxAlarmQueriesPerRefreshInterval);
@@ -528,7 +528,7 @@ public class DefaultTbEntityDataSubscriptionService implements TbEntityDataSubsc
     }
 
     private TbAlarmCountSubCtx createSubCtx(WebSocketSessionRef sessionRef, AlarmCountCmd cmd) {
-        Map<Integer, TbAbstractSubCtx> sessionSubs = subscriptionsBySessionId.computeIfAbsent(sessionRef.getSessionId(), k -> new HashMap<>());
+        Map<Integer, TbAbstractSubCtx> sessionSubs = subscriptionsBySessionId.computeIfAbsent(sessionRef.getSessionId(), k -> new ConcurrentHashMap<>());
         TbAlarmCountSubCtx ctx = new TbAlarmCountSubCtx(serviceId, wsService, entityService, localSubscriptionService,
                 attributesService, stats, alarmService, sessionRef, cmd.getCmdId());
         if (cmd.getQuery() != null) {
diff --git a/application/src/main/java/org/thingsboard/server/service/subscription/DefaultTbLocalSubscriptionService.java b/application/src/main/java/org/thingsboard/server/service/subscription/DefaultTbLocalSubscriptionService.java
index bbfdd2d44f..1e701c7b5c 100644
--- a/application/src/main/java/org/thingsboard/server/service/subscription/DefaultTbLocalSubscriptionService.java
+++ b/application/src/main/java/org/thingsboard/server/service/subscription/DefaultTbLocalSubscriptionService.java
@@ -85,7 +85,7 @@ import java.util.stream.Collectors;
 @Service
 public class DefaultTbLocalSubscriptionService implements TbLocalSubscriptionService {
 
-    private final ConcurrentMap<String, Map<Integer, TbSubscription<?>>> subscriptionsBySessionId = new ConcurrentHashMap<>();
+    private final ConcurrentMap<String, ConcurrentMap<Integer, TbSubscription<?>>> subscriptionsBySessionId = new ConcurrentHashMap<>();
     private final ConcurrentMap<UUID, TbEntityLocalSubsInfo> subscriptionsByEntityId = new ConcurrentHashMap<>();
     private final ConcurrentMap<UUID, TbEntityUpdatesInfo> entityUpdates = new ConcurrentHashMap<>();
 
diff --git a/rule-engine/rule-engine-components/src/main/java/org/thingsboard/rule/engine/rest/TbHttpClient.java b/rule-engine/rule-engine-components/src/main/java/org/thingsboard/rule/engine/rest/TbHttpClient.java
index f8ec81abcf..d7476bf08e 100644
--- a/rule-engine/rule-engine-components/src/main/java/org/thingsboard/rule/engine/rest/TbHttpClient.java
+++ b/rule-engine/rule-engine-components/src/main/java/org/thingsboard/rule/engine/rest/TbHttpClient.java
@@ -135,7 +135,6 @@ public class TbHttpClient {
 
             this.webClient = WebClient.builder()
                     .clientConnector(new ReactorClientHttpConnector(httpClient))
-                    .defaultHeader(HttpHeaders.CONNECTION, "close") //In previous realization this header was present! (Added for hotfix "Connection reset")
                     .codecs(configurer -> configurer.defaultCodecs().maxInMemorySize(
                             (config.getMaxInMemoryBufferSizeInKb() > 0 ? config.getMaxInMemoryBufferSizeInKb() : 256) * 1024))
                     .build();