My goal is to send a UDP message (smaller than 100 bytes) from a SmartWatch (running wear os 2) to an Arduino on the same network. As long as the SmartWatch stays connected to the wifi (ip address of the watch: 145.167.189.23) this works great. But when I turn on bluetooth, the SmartWatch disables wifi and switches to an internet connection via the bluetooth connected phone. The SmartWatch gets an ip address in a subnet of the internet connection from the mobile (if the mobile has the ip address 145.167.189.105, it gets 145.167.177.4). TCP requests, like 'stackoverflow.com' work fine.
If I now try to send a UDP message nothing arrives at the Arduino. I already tried to send a UDP message to 255.255.255.255, 145.255.255.255, 145.167.255.255, 145.167.189.255, but nothing ever arrived at the Arduino ( verified by Wireshark). Over six years ago there was the same problem (Simple UDP Broadcast not working on Android Wear), at that time wear os 2 was not available. The only proposed solution was the 'Wear Data Layer'. I already tried this as well, but observed very large latencies (about 3 seconds). Therefore, these do not represent a solution for me at all.
The documentation for network access on wear os only says
You can use protocols such as HTTP, TCP, and UDP
Maybe someone could give me a hint why the UDP messages are not forwarded from the phone.
Only DNS udp packages can be forwarded to the phone.