i have worked on lpc2388 ethernet. I have used RTL library and ethernet interface UDP protocol example file is tested, found ok.
I have replaced lpc2388FBD144 IC with lpc1788FBD144 but i am unable prove ethernet interface UDP protocol using KEIL examples.
Please look into this matter
How should someone 'look into this matter' without knowing your hardware and application? There are so many configuration options, such as clock tree configuration, external oscillator or external PHY.
We have one example project for a LPC1768 in the folder C:\Keil_v5\ARM\Boards\Keil\MCB1700\RL\TCPnet\LEDClientThis example handles a UDP protocol. You can compare your application with this example. Then you can evaluate some differences.