Hi folks. When I try to use the Unity sample projects over LAN, I get an unusual error . . .
message->m_Block->allocatedLength == sizeof(PingPacket)
. . . when I try to connect via UNet between a Mac and a Windows machine. Over here, it seems that others who faced this issue fixed by using just a Windows-to-Windows connection. That worked for me too.
But that’s really inconvenient. I purposefully have Windows and Mac and Linux machines to test whether they can work together. Does UNet really not work cross-platform? Why? How is that compatible with Unity’s vision of easy cross-platform portability?
On a more practical note, has anyone found a fix for this? If not, is anyone aware if a fix is coming?
I’ve got a similar issue to this, and I’d love to hear someone from Unity address the issue. I’m getting a timeout error when trying to connect cross platform in my simple game. If either the server or a client is on mac and the other is on windows, I get a networking timeout when trying to connect them with the UNET matchmaker. Using two windows machines or two macs works perfectly.
I get the following error when trying to connect between a Windows machine and a Mac (connecting directly over a LAN):
UNet Client Disconnect Error: BadMessage
UnityEngine.Networking.NetworkIdentity:UNetStaticUpdate()
Windows to Android works fine for me though.
Oops, my problem was that 5.1.2 didn’t want to talk to 5.1.3. With Mac & Windows on the same version of Unity they are connecting fine for me 
If you need help to set things up and the networking documentation is not friendly you make look at my website www.numbapple.com at the top there is a link to CrossNet its free… look at the bottom of the video urls for the link. You may implement it as it is / Learn from the CrossNet section of code / pull parts of it for your project it doesnt matter. Also can find a direct link in my signature.
I am facing a problem where I am trying to connect a project in Windows Laptop with the one on MacBook. They both are on same WiFi network.
When I create a server on Mac, and then try to connect it via windows, it properly spawns a player. However, the opposite is not happening. I am NOT able to keep Windows as a server machine. The Mac Unity shows ‘connecting…’ but doesn’t connects at all.
If I run terminal and write ping 192.168… it is giving response, but Unity is not able to find that windows PC. Any idea what could be the problem???
Most likely it is software firewall settings on your Windows machine. At some point Windows should have asked you a question regarding network access for either your game build or your Unity editor. I forget how the question is phrased, but if you didn’t tell it to allow access you’ll need to manually go into the firewall settings and change them.