diff --git a/test/tap/tap/utils.cpp b/test/tap/tap/utils.cpp
index 1ff246c1d..84bf6d023 100644
--- a/test/tap/tap/utils.cpp
+++ b/test/tap/tap/utils.cpp
@@ -1418,7 +1418,7 @@ const char t_restapi_insert[] {
 		"VALUES (1,%ld,'%s','%s','%s','comm')",
 };
 
-const string base_address { "http://localhost:6070/sync/" };
+const string base_address { "http://proxysql:6070/sync/" };
 
 int configure_endpoints(
 	MYSQL* admin,
@@ -1464,7 +1464,8 @@ int configure_endpoints(
 	int endpoint_timeout = wait_post_enpoint_ready(full_endpoint, "{}", 1000, 100);
 
 	if (endpoint_timeout) {
-		diag("Timeout while trying to reach first valid enpoint");
+		diag("Timeout while trying to reach first valid endpoint: %s", full_endpoint.c_str());
+		diag("This usually means RESTAPI enabled but script failed to execute. Check TAP_WORKDIR.");
 		return EXIT_FAILURE;
 	}
 
diff --git a/test/tap/tests/reg_test_3223-restapi_return_codes-t.cpp b/test/tap/tests/reg_test_3223-restapi_return_codes-t.cpp
index 86c3336d7..be29f7286 100644
--- a/test/tap/tests/reg_test_3223-restapi_return_codes-t.cpp
+++ b/test/tap/tests/reg_test_3223-restapi_return_codes-t.cpp
@@ -31,7 +31,7 @@ using std::vector;
 using hrc = std::chrono::high_resolution_clock;
 using nlohmann::json;
 
-const string base_address { "http://localhost:6070/sync/" };
+const string base_address { "http://proxysql:6070/sync/" };
 
 const vector<honest_req_t> honest_requests {
 	{ { "valid_output_script", "%s.py", "POST", 1000 }, { "{}" } },
@@ -126,11 +126,23 @@ int main(int argc, char** argv) {
 		return EXIT_FAILURE;
 	}
 
+	diag("=== Regression Test #3223: RESTAPI Script Execution & Return Codes ===");
+	diag("This test ensures that ProxySQL RESTAPI correctly handles script execution");
+	diag("and returns the expected HTTP status codes and script exit codes.");
+	diag("The test strategy is:");
+	diag("1. Register multiple valid and faulty scripts in RESTAPI routes.");
+	diag("2. Issue POST/GET requests to these endpoints.");
+	diag("3. Verify HTTP return codes (200 for success, 400/424 for failures).");
+	diag("4. Verify internal script error codes (exit codes, timeouts, signals).");
+	diag("5. Check behavior with large outputs and partial flushes.");
+	diag("=========================================================================");
+
 	plan(count_exp_tests(honest_requests, invalid_requests));
 
 	MYSQL* admin = mysql_init(NULL);
 
 	// Initialize connections
+	diag("Connecting to ProxySQL Admin at %s:%d as %s", cl.host, cl.admin_port, cl.admin_username);
 	if (!admin) {
 		fprintf(stderr, "File %s, line %d, Error: %s\n", __FILE__, __LINE__, mysql_error(admin));
 		return EXIT_FAILURE;
@@ -142,12 +154,14 @@ int main(int argc, char** argv) {
 	}
 
 	// Enable 'RESTAPI'
+	diag("Enabling RESTAPI on port 6070");
 	MYSQL_QUERY(admin, "SET admin-restapi_enabled='true'");
 	MYSQL_QUERY(admin, "SET admin-restapi_port=6070");
 
 	MYSQL_QUERY(admin, "LOAD ADMIN VARIABLES TO RUNTIME");
 
 	// Clean current 'restapi_routes' if any
+	diag("Configuring RESTAPI routes...");
 	MYSQL_QUERY(admin, "DELETE FROM restapi_routes");
 
 	// Configure restapi_routes to be used
@@ -161,18 +175,20 @@ int main(int argc, char** argv) {
 		honest_requests.begin(), honest_requests.end(), std::back_inserter(v_epts_info), ext_v_epts_info
 	);
 
+	diag("Initializing endpoints for valid requests...");
 	int ept_conf_res = configure_endpoints(admin, script_base_path, v_epts_info, dummy_ept, true);
 	if (ept_conf_res) {
 		diag("Endpoint configuration failed. Skipping endpoint testing...");
 		return EXIT_FAILURE;
 	}
 
+	diag("Testing valid RESTAPI requests...");
 	{
 		for (const auto& req : honest_requests) {
 			for (const string& params : req.params) {
 				const string ept { join_path(base_address, req.ept_info.name) };
 				diag(
-					"Checking valid '%s' request - ept: '%s', params: '%s'",
+					"  Checking valid '%s' request - ept: '%s', params: '%s'",
 					req.ept_info.method.c_str(), ept.c_str(), params.c_str()
 				);
 				std::chrono::nanoseconds duration;
@@ -294,12 +310,14 @@ int main(int argc, char** argv) {
 		invalid_requests.begin(), invalid_requests.end(), std::back_inserter(i_epts_info), ext_i_epts_info
 	);
 
+	diag("Initializing endpoints for invalid requests...");
 	ept_conf_res = configure_endpoints(admin, script_base_path, i_epts_info, dummy_ept, true);
 	if (ept_conf_res) {
 		diag("Endpoint configuration failed. Skipping endpoint testing...");
 		return EXIT_FAILURE;
 	}
 
+	diag("Testing invalid RESTAPI requests...");
 	for (const auto& req : invalid_requests) {
 		for (const ept_pl_t& ept_pl : req.ept_pls) {
 			std::chrono::nanoseconds duration;
@@ -308,7 +326,7 @@ int main(int argc, char** argv) {
 
 			const string ept { join_path(base_address, req.ept_info.name) };
 			diag(
-				"Checking valid '%s' request - ept: '%s', params: '%s'",
+				"  Checking invalid '%s' request - ept: '%s', params: '%s'",
 				req.ept_info.method.c_str(), ept.c_str(), ept_pl.params.c_str()
 			);
 
diff --git a/test/tap/tests/reg_test_3591-restapi_num_fds-t.cpp b/test/tap/tests/reg_test_3591-restapi_num_fds-t.cpp
index 13bb29142..d43704bd3 100644
--- a/test/tap/tests/reg_test_3591-restapi_num_fds-t.cpp
+++ b/test/tap/tests/reg_test_3591-restapi_num_fds-t.cpp
@@ -38,6 +38,17 @@ int main(int argc, char** argv) {
 		diag("Failed to get the required environmental variables.");
 		return -1;
 	}
+
+	diag("=== Regression Test #3591: RESTAPI with High Number of FDs ===");
+	diag("This test verifies that the ProxySQL metrics endpoint remains functional");
+	diag("even when a large number of client connections (2047) are opened.");
+	diag("The test strategy is:");
+	diag("1. Elevate process FD limits.");
+	diag("2. Enable RESTAPI on port 6070.");
+	diag("3. Open 2047 concurrent MySQL connections to ProxySQL.");
+	diag("4. Verify that the /metrics endpoint is still reachable.");
+	diag("==============================================================");
+
 	struct rlimit limits { 0, 0 };
 	getrlimit(RLIMIT_NOFILE, &limits);
 	diag("Old process limits: { %ld, %ld }", limits.rlim_cur, limits.rlim_max);
@@ -48,6 +59,7 @@ int main(int argc, char** argv) {
 	MYSQL* admin = mysql_init(NULL);
 
 	// Initialize connections
+	diag("Connecting to ProxySQL Admin at %s:%d as %s", cl.host, cl.admin_port, cl.admin_username);
 	if (!admin) {
 		fprintf(stderr, "File %s, line %d, Error: %s\n", __FILE__, __LINE__, mysql_error(admin));
 		return -1;
@@ -59,12 +71,14 @@ int main(int argc, char** argv) {
 	}
 
 	// Enable 'RESTAPI'
+	diag("Enabling RESTAPI on port 6070");
 	MYSQL_QUERY(admin, "SET admin-restapi_enabled='true'");
 	MYSQL_QUERY(admin, "SET admin-restapi_port=6070");
 	MYSQL_QUERY(admin, "LOAD ADMIN VARIABLES TO RUNTIME");
 
 	std::vector<MYSQL*> mysql_connections {};
 
+	diag("Establishing %d connections to ProxySQL...", NUM_CONNECTIONS);
 	for (int i = 0; i < NUM_CONNECTIONS; i++) {
 		MYSQL* proxy = mysql_init(NULL);
 		if (
@@ -79,11 +93,15 @@ int main(int argc, char** argv) {
 			return EXIT_FAILURE;
 		}
 		mysql_connections.push_back(proxy);
+		if ((i + 1) % 500 == 0) diag("  Established %d/%d connections...", i + 1, NUM_CONNECTIONS);
 	}
+	diag("Connections established.");
 
-	int endpoint_timeout = wait_get_enpoint_ready("http://localhost:6070/metrics/", 1000, 100);
+	diag("Verifying RESTAPI /metrics endpoint via proxysql:6070...");
+	int endpoint_timeout = wait_get_enpoint_ready("http://proxysql:6070/metrics/", 1000, 100);
 	ok(endpoint_timeout == 0, "The endpoint should be available instead of timing out.");
 
+	diag("Closing connections and cleaning up...");
 	for (int i = 0; i < NUM_CONNECTIONS; i++) {
 		mysql_close(mysql_connections[i]);
 	}
diff --git a/test/tap/tests/reg_test_4001-restapi_scripts_num_fds-t.cpp b/test/tap/tests/reg_test_4001-restapi_scripts_num_fds-t.cpp
index b035d8c40..4a4a79791 100644
--- a/test/tap/tests/reg_test_4001-restapi_scripts_num_fds-t.cpp
+++ b/test/tap/tests/reg_test_4001-restapi_scripts_num_fds-t.cpp
@@ -35,7 +35,7 @@ using std::string;
 using std::vector;
 
 const int NUM_CONNECTIONS = 1300;
-const string base_address { "http://localhost:6070/sync/" };
+const string base_address { "http://proxysql:6070/sync/" };
 
 const vector<honest_req_t> honest_requests {
 	{ { "valid_output_script", "%s.py", "POST", 1000 }, { "{}" } },
@@ -56,6 +56,17 @@ int main(int argc, char** argv) {
 		return EXIT_FAILURE;
 	}
 
+	diag("=== Regression Test #4001: RESTAPI with High FD Usage ===");
+	diag("This test verifies that the RESTAPI remains operational when ProxySQL");
+	diag("is handling a large number of concurrent file descriptors (> FD_SETSIZE).");
+	diag("The test strategy is:");
+	diag("1. Elevate process FD limits.");
+	diag("2. Establish 1300 concurrent MySQL connections to ProxySQL.");
+	diag("3. While these connections are held, perform continuous RESTAPI requests.");
+	diag("4. Simultaneously create and destroy additional MySQL connections.");
+	diag("5. Verify that RESTAPI requests and connection operations remain stable.");
+	diag("==========================================================");
+
 	diag("Setting new process limits beyond 'FD_SETSIZE'");
 	struct rlimit limits { 0, 0 };
 	getrlimit(RLIMIT_NOFILE, &limits);
@@ -67,6 +78,7 @@ int main(int argc, char** argv) {
 	MYSQL* admin = mysql_init(NULL);
 
 	// Initialize connections
+	diag("Connecting to ProxySQL Admin at %s:%d as %s", cl.host, cl.admin_port, cl.admin_username);
 	if (!admin) {
 		fprintf(stderr, "File %s, line %d, Error: %s\n", __FILE__, __LINE__, mysql_error(admin));
 		return EXIT_FAILURE;
@@ -77,7 +89,7 @@ int main(int argc, char** argv) {
 		return EXIT_FAILURE;
 	}
 
-	string script_base_path { string { cl.workdir  } + "reg_test_3223_scripts" };
+	const char* d_env = getenv("REGULAR_INFRA_DATADIR"); string script_base_path = (d_env ? string(d_env) + "/reg_test_3223_scripts" : string(cl.workdir) + "reg_test_3223_scripts");
 	const ept_info_t dummy_ept { "dummy_ept_script", "%s.py", "POST", 1000 };
 
 	vector<ept_info_t> v_epts_info {};
@@ -86,6 +98,7 @@ int main(int argc, char** argv) {
 		honest_requests.begin(), honest_requests.end(), std::back_inserter(v_epts_info), ext_v_epts_info
 	);
 
+	diag("Configuring RESTAPI endpoints...");
 	int ept_conf_res = configure_endpoints(admin, script_base_path, v_epts_info, dummy_ept, true);
 	if (ept_conf_res) {
 		diag("Endpoint configuration failed. Skipping endpoint testing...");
@@ -94,6 +107,7 @@ int main(int argc, char** argv) {
 
 	std::vector<MYSQL*> mysql_connections {};
 
+	diag("Establishing %d baseline connections to ProxySQL...", NUM_CONNECTIONS);
 	for (int i = 0; i < NUM_CONNECTIONS; i++) {
 		MYSQL* proxy = mysql_init(NULL);
 		if (!mysql_real_connect(proxy, cl.host, cl.username, cl.password, NULL, cl.port, NULL, 0)) {
@@ -101,7 +115,9 @@ int main(int argc, char** argv) {
 			return EXIT_FAILURE;
 		}
 		mysql_connections.push_back(proxy);
+		if ((i + 1) % 200 == 0) diag("  Established %d/%d connections...", i + 1, NUM_CONNECTIONS);
 	}
+	diag("Baseline connections established.");
 
 	typedef std::chrono::high_resolution_clock hrc;
 	const uint64_t test_duration = 10000;
@@ -111,6 +127,7 @@ int main(int argc, char** argv) {
 	uint64_t conn_count = 0;
 	uint64_t mysql_fails = 0;
 
+	diag("Starting simultaneous RESTAPI requests and connection churn (Duration: %ldms)...", test_duration);
 	{
 		std::thread create_conns([&]() -> int {
 			std::chrono::nanoseconds duration;
@@ -120,7 +137,7 @@ int main(int argc, char** argv) {
 			start = hrc::now();
 
 			while (true) {
-				if (mysql_fails > (conn_count * FAILURE_RATE) / 100) {
+				if (conn_count > 0 && mysql_fails > (conn_count * FAILURE_RATE) / 100) {
 					diag("Too many mysql failures in connection creation, considering test as failed...");
 					conn_creation_res = EXIT_FAILURE;
 					return EXIT_FAILURE;
@@ -129,17 +146,17 @@ int main(int argc, char** argv) {
 				MYSQL* proxy = mysql_init(NULL);
 
 				if (!mysql_real_connect(proxy, cl.host, cl.username, cl.password, NULL, cl.port, NULL, 0)) {
-					fprintf(stderr, "File %s, line %d, Error: %s\n", __FILE__, __LINE__, mysql_error(proxy));
-					mysql_fails += 1;
-				}
-
-				int rc = mysql_query(proxy, "DO 1");
-				if (rc) {
-					diag("mysql_errno: '%d', mysql_error: '%s'", mysql_errno(proxy), mysql_error(proxy));
+					diag("Churn connection failed: %s", mysql_error(proxy));
 					mysql_fails += 1;
+				} else {
+					int rc = mysql_query(proxy, "DO 1");
+					if (rc) {
+						diag("Churn query failed: mysql_errno: '%d', mysql_error: '%s'", mysql_errno(proxy), mysql_error(proxy));
+						mysql_fails += 1;
+					}
+					mysql_close(proxy);
 				}
 
-				mysql_close(proxy);
 				end = hrc::now();
 				duration = end - start;
 
@@ -160,6 +177,7 @@ int main(int argc, char** argv) {
 
 		start = hrc::now();
 
+		int api_request_count = 0;
 		while (true) {
 			int rc = 0;
 
@@ -191,10 +209,13 @@ int main(int argc, char** argv) {
 					}
 
 					if (curl_err == 7) {
-						diag("Operation over endpoint failed with 'CURLE_COULDNT_CONNECT'. Aborting...");
+						diag("Operation over endpoint %s failed with 'CURLE_COULDNT_CONNECT'. Aborting...", ept.c_str());
+						rc = 1;
 						break;
 					}
+					api_request_count++;
 				}
+				if (rc) break;
 			}
 
 			end = hrc::now();
@@ -205,7 +226,9 @@ int main(int argc, char** argv) {
 			}
 		}
 
+		diag("Joining churn thread and cleaning up...");
 		create_conns.join();
+		diag("Churn thread finished. Total API requests: %d, Total churn conns: %ld, Failures: %ld", api_request_count, conn_count, mysql_fails);
 
 		ok(
 			conn_creation_res == EXIT_SUCCESS,