WiFiClient.connect() does fail all the time (ESP8266 Core for Arduino)
If the server has a default IP address of 192.168.0.1 and the client has an IP address of 192.168.4.1 my guess is they won't be able to talk because you are using a 24 bit mask.  

The subnet mask defines the number of bits that makes up the subnet, so if you were using the two addresses above and had a mask of 255.255.255.0 or 24 bits then the subnets you were using would be 192.168.0 and 192.168.4.  To cross subnets you need some form of routing process (usually a router, switch that can route, etc).

So you need to either change the mask or, stick both devices on the same subnet.
(Don't rely on defaults, when they change your code breaks)