How can I get Barrier working between two Windows PCs?

The easiest troubleshooting order is: test both PCs without the VPN, verify they can ping each other, confirm the client points to the server’s LAN IP, and then check Barrier’s logs for connection errors. Once the basic setup works, reconnect the VPN on the client and see whether its split-tunneling or local-network access option allows traffic to the server. VPN settings that block local network access commonly prevent this kind of connection.

First confirm which computer is running as the Barrier server and which is the client. On the client, enter the server computer’s local network IP address—not its VPN address—and make sure the server is listening. Since both machines are using a VPN, the VPN may be routing traffic away from the normal local network or blocking Barrier’s port. Try disconnecting the server from the VPN as a test, then reconnect the client using the server’s regular LAN IP.

Being on the same physical network doesn’t always mean the machines can communicate directly when a VPN is active. Check the client’s server address and use the server’s private LAN address, usually something like 192.168.x.x or 10.x.x.x. Also check Windows Firewall on the server and allow Barrier through it, or temporarily disable the firewall just long enough to test whether it’s the blocker. If it works with the server disconnected from the VPN, you’ve confirmed the VPN routing or firewall rules are causing the issue.