Hello everyone!

I’ve had a strange networking problem that I cant explain. Here’s the situation:

I have a Mac and a Windows PC connected directly to each other using an Ethernet cable.

The Mac is manually set with the IP 10.0.1.1and a subnet mask of 255.255.255.0.

The Windows machine is set to 10.0.0.1with the same subnet mask.

By all standard networking rules, they shouldn’t communicate since they’re configured to be on different subnets. Yet, they are still able to send data to each other.

To add to the context, both machines are also connected to the internet via Wi-Fi through my home router. But for the file transfer over Ethernet, they’re just directly connected—no routers or switches involved.

Here’s what I’ve already considered and checked:

• No additional routes are set up that would explain the cross-subnet communication.
• No link-local addresses (APIPA) are being used for the Ethernet interfaces.
• The Wi-Fi network is on a completely different IP range.

Any Idea what may me be causing this ?

Thanks in advance for your help!