diff --git a/src/test/regress/multi_schedule b/src/test/regress/multi_schedule
index 76b4a112b..5182317f8 100644
--- a/src/test/regress/multi_schedule
+++ b/src/test/regress/multi_schedule
@@ -66,7 +66,16 @@ test: multi_partitioning_utils multi_partitioning replicated_partitioned_table
 # ----------
 # Tests for recursive subquery planning
 # ----------
-test: subquery_basics subquery_local_tables subquery_executors subquery_and_cte set_operations set_operation_and_local_tables
+# NOTE: The next 6 were in parallel originally, but we got "too many
+# connection" errors on CI. Requires investigation before doing them in
+# parallel again.
+test: subquery_basics
+test: subquery_local_tables
+test: subquery_executors
+test: subquery_and_cte
+test: set_operations
+test: set_operation_and_local_tables
+
 test: subqueries_deep subquery_view subquery_partitioning subquery_complex_target_list subqueries_not_supported subquery_in_where
 test: non_colocated_leaf_subquery_joins non_colocated_subquery_joins non_colocated_join_order
 test: subquery_prepared_statements pg12 cte_inline