Why do no data show up on the UDP port?

An external device is constantly sending UDP packets. Arriving packets are listed by Wireshark.

524887 58.405607 192.168.33.180 192.168.33.30 UDP 1508 1024 → 4098 Len=1466

Matlab connects to a UDP socket

u=udpport("localhost","192.168.33.30","LocalPort",4096,"EnablePortSharing",true)

u =

UDPPort with properties:

IPAddressVersion: "IPV4"

LocalHost: "192.168.33.30"

LocalPort: 4096

NumBytesAvailable: 0

Even though UDP packets keep coming in u.NumBytesAvailable stays 0.

[Harald Gomm]

It does not work with LocalPort 4098 either.

[Krishan Bhakta]

Any updates on whether you were able to figure out the issue?

Answer 1

[Vidip]

The packets can be rejected due to the MAC address mismatch between the remote device and address of your ethernet adapter. Apart from this, the localhost address typically refers to 127.0.0.1, which is the loopback address and not the same as your machine's local network IP. Make sure you're binding to the correct IP address that the UDP packets are being sent to. If the packets are being sent to 192.168.33.30, then you should use that IP when creating the udpport.

Also, check if your firewall settings are allowing incoming UDP packets on the port you're listening to. Firewalls can block incoming traffic, which would prevent MATLAB from receiving the packets.