diff --git a/apps/emqx_connector/src/emqx_connector_mongo.erl b/apps/emqx_connector/src/emqx_connector_mongo.erl
index 5bfcbe009..778abf8c2 100644
--- a/apps/emqx_connector/src/emqx_connector_mongo.erl
+++ b/apps/emqx_connector/src/emqx_connector_mongo.erl
@@ -47,6 +47,10 @@
     default_port => ?MONGO_DEFAULT_PORT
 }).
 
+-ifdef(TEST).
+-export([to_servers_raw/1]).
+-endif.
+
 %%=====================================================================
 roots() ->
     [
@@ -447,7 +451,7 @@ may_parse_srv_and_txt_records_(
         true ->
             error({missing_parameter, replica_set_name});
         false ->
-            Config#{hosts => servers_to_bin(Servers)}
+            Config#{hosts => servers_to_bin(lists:flatten(Servers))}
     end;
 may_parse_srv_and_txt_records_(
     #{
@@ -557,9 +561,33 @@ to_servers_raw(Servers) ->
         fun(Server) ->
             emqx_connector_schema_lib:parse_server(Server, ?MONGO_HOST_OPTIONS)
         end,
-        string:tokens(str(Servers), ", ")
+        split_servers(Servers)
     ).
 
+split_servers(L) when is_list(L) ->
+    PossibleTypes = [
+        list(binary()),
+        list(string()),
+        string()
+    ],
+    TypeChecks = lists:map(fun(T) -> typerefl:typecheck(T, L) end, PossibleTypes),
+    case TypeChecks of
+        [ok, _, _] ->
+            %% list(binary())
+            lists:map(fun binary_to_list/1, L);
+        [_, ok, _] ->
+            %% list(string())
+            L;
+        [_, _, ok] ->
+            %% string()
+            string:tokens(L, ", ");
+        [_, _, _] ->
+            %% invalid input
+            throw("List of servers must contain only strings")
+    end;
+split_servers(B) when is_binary(B) ->
+    string:tokens(str(B), ", ").
+
 str(A) when is_atom(A) ->
     atom_to_list(A);
 str(B) when is_binary(B) ->
diff --git a/apps/emqx_connector/test/emqx_connector_mongo_tests.erl b/apps/emqx_connector/test/emqx_connector_mongo_tests.erl
new file mode 100644
index 000000000..7978ed289
--- /dev/null
+++ b/apps/emqx_connector/test/emqx_connector_mongo_tests.erl
@@ -0,0 +1,168 @@
+%%--------------------------------------------------------------------
+%% Copyright (c) 2022 EMQ Technologies Co., Ltd. All Rights Reserved.
+%%
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%%--------------------------------------------------------------------
+
+-module(emqx_connector_mongo_tests).
+
+-include_lib("eunit/include/eunit.hrl").
+
+-define(DEFAULT_MONGO_PORT, 27017).
+
+%%------------------------------------------------------------------------------
+%% Helper fns
+%%------------------------------------------------------------------------------
+
+%%------------------------------------------------------------------------------
+%% Test cases
+%%------------------------------------------------------------------------------
+
+to_servers_raw_test_() ->
+    [
+        {"single server, binary, no port",
+            ?_test(
+                ?assertEqual(
+                    [{"localhost", ?DEFAULT_MONGO_PORT}],
+                    emqx_connector_mongo:to_servers_raw(<<"localhost">>)
+                )
+            )},
+        {"single server, string, no port",
+            ?_test(
+                ?assertEqual(
+                    [{"localhost", ?DEFAULT_MONGO_PORT}],
+                    emqx_connector_mongo:to_servers_raw("localhost")
+                )
+            )},
+        {"single server, list(binary), no port",
+            ?_test(
+                ?assertEqual(
+                    [{"localhost", ?DEFAULT_MONGO_PORT}],
+                    emqx_connector_mongo:to_servers_raw([<<"localhost">>])
+                )
+            )},
+        {"single server, list(string), no port",
+            ?_test(
+                ?assertEqual(
+                    [{"localhost", ?DEFAULT_MONGO_PORT}],
+                    emqx_connector_mongo:to_servers_raw(["localhost"])
+                )
+            )},
+        %%%%%%%%%
+        {"single server, binary, with port",
+            ?_test(
+                ?assertEqual(
+                    [{"localhost", 9999}], emqx_connector_mongo:to_servers_raw(<<"localhost:9999">>)
+                )
+            )},
+        {"single server, string, with port",
+            ?_test(
+                ?assertEqual(
+                    [{"localhost", 9999}], emqx_connector_mongo:to_servers_raw("localhost:9999")
+                )
+            )},
+        {"single server, list(binary), with port",
+            ?_test(
+                ?assertEqual(
+                    [{"localhost", 9999}],
+                    emqx_connector_mongo:to_servers_raw([<<"localhost:9999">>])
+                )
+            )},
+        {"single server, list(string), with port",
+            ?_test(
+                ?assertEqual(
+                    [{"localhost", 9999}], emqx_connector_mongo:to_servers_raw(["localhost:9999"])
+                )
+            )},
+        %%%%%%%%%
+        {"multiple servers, string, no port",
+            ?_test(
+                ?assertEqual(
+                    [{"host1", ?DEFAULT_MONGO_PORT}, {"host2", ?DEFAULT_MONGO_PORT}],
+                    emqx_connector_mongo:to_servers_raw("host1, host2")
+                )
+            )},
+        {"multiple servers, binary, no port",
+            ?_test(
+                ?assertEqual(
+                    [{"host1", ?DEFAULT_MONGO_PORT}, {"host2", ?DEFAULT_MONGO_PORT}],
+                    emqx_connector_mongo:to_servers_raw(<<"host1, host2">>)
+                )
+            )},
+        {"multiple servers, list(string), no port",
+            ?_test(
+                ?assertEqual(
+                    [{"host1", ?DEFAULT_MONGO_PORT}, {"host2", ?DEFAULT_MONGO_PORT}],
+                    emqx_connector_mongo:to_servers_raw(["host1", "host2"])
+                )
+            )},
+        {"multiple servers, list(binary), no port",
+            ?_test(
+                ?assertEqual(
+                    [{"host1", ?DEFAULT_MONGO_PORT}, {"host2", ?DEFAULT_MONGO_PORT}],
+                    emqx_connector_mongo:to_servers_raw([<<"host1">>, <<"host2">>])
+                )
+            )},
+        %%%%%%%%%
+        {"multiple servers, string, with port",
+            ?_test(
+                ?assertEqual(
+                    [{"host1", 1234}, {"host2", 2345}],
+                    emqx_connector_mongo:to_servers_raw("host1:1234, host2:2345")
+                )
+            )},
+        {"multiple servers, binary, with port",
+            ?_test(
+                ?assertEqual(
+                    [{"host1", 1234}, {"host2", 2345}],
+                    emqx_connector_mongo:to_servers_raw(<<"host1:1234, host2:2345">>)
+                )
+            )},
+        {"multiple servers, list(string), with port",
+            ?_test(
+                ?assertEqual(
+                    [{"host1", 1234}, {"host2", 2345}],
+                    emqx_connector_mongo:to_servers_raw(["host1:1234", "host2:2345"])
+                )
+            )},
+        {"multiple servers, list(binary), with port",
+            ?_test(
+                ?assertEqual(
+                    [{"host1", 1234}, {"host2", 2345}],
+                    emqx_connector_mongo:to_servers_raw([<<"host1:1234">>, <<"host2:2345">>])
+                )
+            )},
+        %%%%%%%%
+        {"multiple servers, invalid list(string)",
+            ?_test(
+                ?assertThrow(
+                    _,
+                    emqx_connector_mongo:to_servers_raw(["host1, host2"])
+                )
+            )},
+        {"multiple servers, invalid list(binary)",
+            ?_test(
+                ?assertThrow(
+                    _,
+                    emqx_connector_mongo:to_servers_raw([<<"host1, host2">>])
+                )
+            )},
+        %% TODO: handle this case??
+        {"multiple servers, mixed list(binary|string)",
+            ?_test(
+                ?assertThrow(
+                    _,
+                    emqx_connector_mongo:to_servers_raw([<<"host1">>, "host2"])
+                )
+            )}
+    ].