When running an ESP in AT mode (WiFi Shield) I found I need to use this in order to use Blynk.config()
on the Arduino.
#include <ESP8266_Lib.h> // ESP-01 Link
#include <BlynkSimpleShieldEsp8266.h> // ESP-01 Link
wifi.setDHCP(1, 1, 1); //Enable dhcp in station mode and save in flash of esp8266
Blynk.config(wifi, auth, server, port);
if (Blynk.connectWiFi(ssid, pass)) {
Blynk.connect();
}