diff --git a/apps/emqx/src/emqx_shared_sub.erl b/apps/emqx/src/emqx_shared_sub.erl
index 87d0554c0..84921be6b 100644
--- a/apps/emqx/src/emqx_shared_sub.erl
+++ b/apps/emqx/src/emqx_shared_sub.erl
@@ -171,6 +171,10 @@ strategy(Group) ->
             get_default_shared_subscription_strategy()
     end.
 
+-spec ack_enabled() -> boolean().
+ack_enabled() ->
+    emqx:get_config([broker, shared_dispatch_ack_enabled], false).
+
 do_dispatch(SubPid, _Group, Topic, Msg, _Type) when SubPid =:= self() ->
     %% Deadlock otherwise
     SubPid ! {deliver, Topic, Msg},
@@ -182,8 +186,14 @@ do_dispatch(SubPid, _Group, Topic, #message{qos = ?QOS_0} = Msg, _Type) ->
 do_dispatch(SubPid, _Group, Topic, Msg, retry) ->
     %% Retry implies all subscribers nack:ed, send again without ack
     send(SubPid, Topic, {deliver, Topic, Msg});
-do_dispatch(SubPid, _Group, Topic, Msg, fresh) ->
-    send(SubPid, Topic, {deliver, Topic, Msg}).
+do_dispatch(SubPid, Group, Topic, Msg, fresh) ->
+    case ack_enabled() of
+        true ->
+            %% TODO: delete this case after 5.1.0
+            do_dispatch_with_ack(SubPid, Group, Topic, Msg);
+        false ->
+            send(SubPid, Topic, {deliver, Topic, Msg})
+    end.
 
 -spec do_dispatch_with_ack(pid(), emqx_types:group(), emqx_types:topic(), emqx_types:message()) ->
     ok | {error, _}.
diff --git a/apps/emqx/test/emqx_config_SUITE.erl b/apps/emqx/test/emqx_config_SUITE.erl
index 5e9284a41..3de081df8 100644
--- a/apps/emqx/test/emqx_config_SUITE.erl
+++ b/apps/emqx/test/emqx_config_SUITE.erl
@@ -440,6 +440,7 @@ zone_global_defaults() ->
                 server_keepalive => disabled,
                 session_expiry_interval => 7200000,
                 shared_subscription => true,
+                shared_subscription_strategy => round_robin,
                 strict_mode => false,
                 upgrade_qos => false,
                 use_username_as_clientid => false,
diff --git a/apps/emqx/test/emqx_shared_sub_SUITE.erl b/apps/emqx/test/emqx_shared_sub_SUITE.erl
index 7c6c144eb..d4bb9bbea 100644
--- a/apps/emqx/test/emqx_shared_sub_SUITE.erl
+++ b/apps/emqx/test/emqx_shared_sub_SUITE.erl
@@ -769,12 +769,12 @@ t_qos1_random_dispatch_if_all_members_are_down(Config) when is_list(Config) ->
 %% Expected behaviour:
 %% the messages sent to client1's inflight and mq are re-dispatched after client1 is down
 t_dispatch_qos2({init, Config}) when is_list(Config) ->
+    ok = ensure_config(round_robin, _AckEnabled = false),
     emqx_config:put_zone_conf(default, [mqtt, max_inflight], 1),
     Config;
 t_dispatch_qos2({'end', Config}) when is_list(Config) ->
     emqx_config:put_zone_conf(default, [mqtt, max_inflight], 0);
 t_dispatch_qos2(Config) when is_list(Config) ->
-    ok = ensure_config(round_robin, _AckEnabled = false),
     Topic = <<"foo/bar/1">>,
     ClientId1 = <<"ClientId1">>,
     ClientId2 = <<"ClientId2">>,
@@ -923,12 +923,12 @@ t_session_takeover(Config) when is_list(Config) ->
     ok.
 
 t_session_kicked({init, Config}) when is_list(Config) ->
+    ok = ensure_config(round_robin, _AckEnabled = false),
     emqx_config:put_zone_conf(default, [mqtt, max_inflight], 1),
     Config;
 t_session_kicked({'end', Config}) when is_list(Config) ->
     emqx_config:put_zone_conf(default, [mqtt, max_inflight], 0);
 t_session_kicked(Config) when is_list(Config) ->
-    ok = ensure_config(round_robin, _AckEnabled = false),
     Topic = <<"foo/bar/1">>,
     ClientId1 = <<"ClientId1">>,
     ClientId2 = <<"ClientId2">>,
@@ -1019,12 +1019,12 @@ ensure_config(Strategy) ->
     ensure_config(Strategy, _AckEnabled = true).
 
 ensure_config(Strategy, AckEnabled) ->
-    emqx_config:put([broker, shared_subscription_strategy], Strategy),
+    emqx_config:put([mqtt, shared_subscription_strategy], Strategy),
     emqx_config:put([broker, shared_dispatch_ack_enabled], AckEnabled),
     ok.
 
 ensure_node_config(Node, Strategy) ->
-    rpc:call(Node, emqx_config, force_put, [[broker, shared_subscription_strategy], Strategy]).
+    rpc:call(Node, emqx_config, force_put, [[mqtt, shared_subscription_strategy], Strategy]).
 
 ensure_group_config(Group2Strategy) ->
     lists:foreach(