Arduino ethernet + uno poor performance

I am using uno with Arduino ethernet V1 (Wiznet W5100) shield. I wrote a simple TCP client code and tested with a TCP server. But my code takes 3-4 tries to make connection to server and frequently disconnects from router or disconnects from server when server sends data fast. I thought problem might be with my code so I tried out Arduino sample code of telnet client Telnet client and with this code also board has same problem. I made no changes to sample code and used as it is for testing. The client is able to receive data 2-3 times only from server and then it disconnects and I have to restart board. Is this because of uno having low memory and low speed microcontroller? I have checked ethernet cable and it's working fine. I am using Hercules Setup Utility as TCP server so there shouldn't be any problem with server. Any help to resolve problem?

Can you try a different Wiznet shield? What is hosting the server?

I have tried different Wiznet shield but same behaviour. I am using this software Hercules SETUP utility | HW-group.com as test TCP server running on local lan pc.

Sorry I am not familiar with the Hercules SETUP utility and and do not have the knowledge help you any further.

How is your Arduino connected to your PC? If using an ethernet switch or router what make/model is in use. We have had previous problems with certain switches (some Cisco models I believe) giving problems with Arduino Ethernet shields.

Can you try another Arduino, just in case it is a problem with the Arduino in some way?

You should not have performance problems of the kind you describe when using an Arduino with Ethernet shield.

Like Gilshultz, I am not familiar with the Hercules software, though I know others have had problems when using it - but cannot remember why. Could you try an alternative just for testing purposes?