Index: source3/auth/auth_util.c
===================================================================
--- source3/auth/auth_util.c.orig
+++ source3/auth/auth_util.c
@@ -563,6 +563,7 @@ NTSTATUS make_server_info_pw(struct auth
 	char *qualified_name = NULL;
 	TALLOC_CTX *mem_ctx = NULL;
 	struct dom_sid u_sid;
+	struct dom_sid g_sid;
 	enum lsa_SidType type;
 	struct auth_serversupplied_info *result;
 
@@ -584,9 +585,14 @@ NTSTATUS make_server_info_pw(struct auth
 		return NT_STATUS_NO_MEMORY;
 	}
 
-	qualified_name = talloc_asprintf(mem_ctx, "%s\\%s",
-					unix_users_domain_name(),
-					unix_username );
+	if (strchr_m(unix_username, *lp_winbind_separator()) == NULL) {
+		qualified_name = talloc_asprintf(mem_ctx, "%s%s%s",
+						unix_users_domain_name(),
+						lp_winbind_separator(),
+						unix_username);
+	} else {
+		qualified_name = talloc_strdup(mem_ctx, unix_username);
+	}
 	if (!qualified_name) {
 		TALLOC_FREE(mem_ctx);
 		return NT_STATUS_NO_MEMORY;
@@ -622,6 +628,12 @@ NTSTATUS make_server_info_pw(struct auth
 	/* set the user sid to be the calculated u_sid */
 	pdb_set_user_sid(sampass, &u_sid, PDB_SET);
 
+	/* samu_to_SamInfo3() calls get_primary_group_sid() if we fail to map */
+	gid_to_sid(&g_sid, pwd->pw_gid);
+	if (!is_null_sid(&g_sid)) {
+		pdb_set_group_sid(sampass, &g_sid, PDB_SET);
+	}
+
 	result = make_server_info(NULL);
 	if (result == NULL) {
 		TALLOC_FREE(sampass);
Index: source3/passdb/lookup_sid.c
===================================================================
--- source3/passdb/lookup_sid.c.orig
+++ source3/passdb/lookup_sid.c
@@ -55,8 +55,7 @@ bool lookup_name(TALLOC_CTX *mem_ctx,
 		return false;
 	}
 
-	p = strchr_m(full_name, '\\');
-
+	p = strchr_m(full_name, *lp_winbind_separator());
 	if (p != NULL) {
 		domain = talloc_strndup(tmp_ctx, full_name,
 					PTR_DIFF(p, full_name));