This may be even more fun than you expect. We were doing VLANs using hardware from a major vendor to partition a network and discovered that while the VLANs worked most of the time, they were leaky with ARP traffic. It was causing us headaches because the machines were supposed to be sending all of their traffic through the router, but sometimes they were seeing ARP replies that they shouldn't and were thinking that the other machines would be reachable directly, causing them to be unable to send traffic until the ARP cache entry timed out. We couldn't get the vendor to show any interest in fixing the bug either, because they were too big to care.
It's possible this chat app could break through VLANs in certain circumstances.
This is interesting to me for basically the same reason — being able to send and receive ARP messages with arbitrary payloads would definitely make troubleshooting VLANs (and other L2 connectivity) easier!
It's possible this chat app could break through VLANs in certain circumstances.