The server.available() in Arduino networking libraries returns always the first connected client. This is in contrary with ESP8266 and ESP32 WiFi libraries for Arduino. They flag the returned connection as claimed and don't return it again. If the WiFiClient on ESP goes out of scope it is closed. In Arduino libraries you must stop() the Client to close the connection and free the 'socket'.

The Arduino Ethernet library has a new function not adopted yet by the WiFi libraries. It is server.accept(). It marks the connection as accepted and the next call doesn't return the same client. The sketch is still responsible to call stop(). The use of accept() is demonstrated in AdvancedChatServer example of the Ethernet library 2.00.

Get the connection (WiFiClient) handle the request, send the response and stop() the connection. Then handle the next Client. Set Expires header to let browser cache the static files.

The server.available() in Arduino networking libraries returns always the first connected client. This is in contrary with ESP8266 and ESP32 WiFi libraries for Arduino. They flag the returned connection as claimed and don't return it again. If the WiFiClient on ESP goes out of scope it is closed. In Arduino libraries you must stop() the Client to close the connection and free the 'socket'.

The Arduino Ethernet library has a new function not adopted yet by the WiFi libraries. It is server.accept(). It marks the connection as accepted and the next call doesn't return the same client. The sketch is still responsible to call stop(). The use of accept() is demonstrated in AdvancedChatServer example of the Ethernet library 2.00.

What you can do? Get the connection (WiFiClient), handle the request, send the response and stop() the connection. Then handle the next Client. Set Expires header to let browser cache the static files.