This is a working example for the depreciated string based API mbed server socket function. Solid on LPC1768. I have included a 32k favicon file for web page stability. Multiple simultaneous connections are no issue here.

Dependencies:   NTPclient

Revision:
0:8e3c163d3dbb
Child:
1:b7b5017e8d01
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed_app.json	Sat Jun 13 13:19:17 2020 +0000
@@ -0,0 +1,31 @@
+{
+    "config": {
+        "main-stack-size": {
+            "value": 8192
+        }
+    },
+    
+    "target_overrides": {
+        "*": {            
+            "platform.stdio-baud-rate": 115200,
+            "platform.stdio-convert-newlines": true,
+            "nsapi.default-wifi-security": "WPA_WPA2",
+            "nsapi.default-wifi-ssid": "\"MolinoMetz\"",
+            "nsapi.default-wifi-password": "\"36693557\""
+        },
+        "NUCLEO_F767ZI": {
+            "target.network-default-interface-type" : "ETHERNET",
+            "esp8266.serial-baudrate"           : 115200,
+            "esp8266.tx"                        : "D1",
+            "esp8266.rx"                        : "D0",
+            "esp8266.provide-default"           : true
+        },
+        "NUCLEO_H743ZI2": {
+            "target.network-default-interface-type" : "ETHERNET",
+            "esp8266.serial-baudrate"           : 115200,
+            "esp8266.tx"                        : "D1",
+            "esp8266.rx"                        : "D0",
+            "esp8266.provide-default"           : true
+        }
+    }
+}