"          DevEui"
              "        </td><td>";
    buffer << "          <input type=\"text\" readonly name=\"DevEui\" id=\"DevEui\" size=\"23\" value=\"";    
    for (int i = 0; i < 8; i++) {
        if (i != 0) {
            buffer << ":";
        }
        buffer << std::uppercase << std::setfill('0') << std::setw(2) << std::hex << (int)devEui[i];
    }
    buffer << "\"> (readonly)";
    buffer << "        </td>"
              "      </tr><tr>"
              "        <td>"
              "          AppEui"
              "        </td><td>";
    buffer << "          <input type=\"text\" name=\"AppEui\" id=\"AppEui\" size=\"23\" value=\"";    
    for (int i = 0; i < 8; i++) {
        if (i != 0) {
            buffer << ":";
        }
        buffer << std::uppercase << std::setfill('0') << std::setw(2) << std::hex << (int)myConfig.appEui[i];
    }
    buffer << "\">";
    buffer << "        </td>"
              "      </tr><tr>"
              "        <td>"
              "          AppKey"
              "        </td><td>";
    buffer << "          <input type=\"text\" name=\"AppKey\" id=\"AppKey\" size=\"47\" value=\"";    
    for (int i = 0; i < 16; i++) {
        if (i != 0) {
            buffer << ":";
        }
        buffer << std::uppercase << std::setfill('0') << std::setw(2) << std::hex << (int)myConfig.appKey[i];
    }
    buffer << "\">";





static void handleConfigSave() {
    char *arg1 = (char*)server.arg("AppEui").c_str();
    Serial.printf("AppEui: %s\n\r", arg1);
    parseField(arg1, 1, 8, myConfig.appEui);

    if (!configParsingFailed) {
        char *arg2 = (char*)server.arg("AppKey").c_str();
        Serial.printf("AppKey: %s\n\r", arg2);
        parseField(arg2, 2, 16, myConfig.appKey);
    }

    configSaved = !configParsingFailed;
    server.sendHeader("Location", String("/"), true);
    server.send(302, "text/plain", "");
}