I want to use my TSU9600 to communicate with a Arcam AVR600 receiver through the LAN on port 50001. This works perfectly fine from my desktop computer which is in the same LAN as the Pronto.

However, when I do a

socket.connect('192.168.8.114', 50001, 3000)

it times out with: "Connection failed"
I know that it actually did connect because the Arcam stops taking connections from my desktop computer after I run the ProntoScript. This means it has an active connection. It only supports one connection at a time.

It looks like the Pronto somehow does not detect a connection being connected to the Arcam. Other connections work just fine ("Google.com",80,3000) etc.

Sync/Async doesn't make a difference.

Does anyone have an idea apart from building a proxy service that forwards the traffic to the Arcam?

Just something. I quickly ran through the user's manual, but did not encounter a line that says: "Network usable for control", this is what I see:
Quote:

"Te AVR600 and AV888 are ftted with a network audio
client (optional for the AVR500) which is capable of
playing internet radio stations as well as stored music
on a network storage device such as a PC, or on a USB
fash drive."
"Control of the AVR500, AVR600 or the AV888 is
either by front panel control buttons, IR remote control
or RS232 port"

From this I can only see that the receiver can work as a client, so it is able to stream music I doubt it has an embedded web server. Are you sure you can control it over the network? Do you have any additional documentation?

I know I have not answered your question why the tsu does not want to connect (ok maybe I did, hint: client), but I think it is futile to try to connect to something you can't control.

There's nothing on controlling the AVR600 in the consumers manual, but this document explains it:
[Link: arcam.co.uk]

It can be controlled through RS232 and IP:
"Controlling theAVR500/AVR600/AV888 via Telnet
It is possible to control theAVR500/AVR600/AV888 via a Telnet session on port 50001 of the IP address of the unit (this can be found in the network
section of the menu). All commands and responses are the same as for RS232 control."

I managed to control it from my desktop PC, so it does work, but just not from my Pronto.

Ok that's something else.

You said that it times out, so I guess the pronto says this.

You can try 2 things:
- wrap the connect in a try-catch state and see the error
- follow the traffic with Wireshark and see why the connection is not established. Maybe the Receiver refuses the connection.

The choice of the 50001 port is very odd.

Sorry but can't help you further as I don't have the receiver.