udpsend bug ?

Francois Weber's icon

Hi,

I am experiencing a strange issue with [udpsend] in the current version of Max 9 on macOS.

The same patch works normally in Max 8: OSC messages are received by an ESP32-S3 when sent to its unicast IP address.

In Max 9, however:

- Broadcast works:

[udpsend 192.168.1.255 <port>]

- Unicast does not work:

[udpsend 192.168.1.20 <port>]

The receiver is an ESP32-S3, so there is no firewall on the receiving side. The ESP32 receives the broadcast packets correctly, but receives nothing when Max 9 is set to the specific IP address.

I also ran the following on the Mac while triggering the unicast message from Max 9:

sudo tcpdump -n -i en0 'udp and dst host 192.168.1.20 and dst port <port>'

tcpdump starts listening, but no matching packet is shown. This suggests that the unicast UDP packet is not leaving Max 9 at all.

Max 8, using the same patch, Mac, network, ESP32 IP address, and port, sends unicast correctly.

Has anyone else encountered a Max 9 / macOS issue where [udpsend] can broadcast but does not send unicast UDP packets? Is there a known permission, regression, or workaround?

System:

- macOS: 26.5.2

- Max: 9.1.5

- Network: Wi-Fi

- ESP32-S3 IP: 192.168.1.20

- UDP/OSC port: 8000

Jan M's icon

you probably checked that already: could you verify that the port is not uses by any other application and/or there is no IP address conflict in your network?

Did you try other ports?

Francois Weber's icon

Hi Jan,

Thank you for your answer.

Yes, I have already tested with ports 8000, 9000 and 7000. These ports are free, no IP address conflict.

Same thing, no change....