Arduino Ethernet Shield 2 Socket Limit

Projects Networking, Protocols, and Devices
1

I'm using an Arduino Ethernet Shield 2 and the datasheet says that it supports up to eight simultaneous socket connections. My questions is what happens when there are more than eight connections, are the connections queued, waiting for a free socket or are they rejected?

2

From memory I thought it was only four sockets. Guessing, I expect that any attempt to connect when there is no capacity is just rejected. Try it and see.

3

yes there are max 8 'slots' for socket data in W5500. it is a memory reserved to hold the information about the socket.

If the firmware can't allocate a 'slot' for incoming TCP connection it refuses the connection.

4

I have test with netcat (nc ) to open connections from Linux to the Arduino W5500 and it only open 4 connectios, it's a little weird because it is supposed to be 8. So I don't know if netcat or the W5500 open 2 sockets per connection.

5

the library configures the count of socket slots. what library do you use?
It looks like the Ethernet library sets 4 for Uno

6

Thanks, I change that in Ethernet.h and now I can open 8 connections.