GL-AXT1800 Computer VPN connection issue

I have two MacBook Pro computers connected to GL-AXT1800. When I use the MAC VPN client to connect to the remote site, one MacBook Pro can successfully connect, but the other cannot. How can I resolve this issue?

Which client do you use? What config do you use?
What do the logs on the router tell about it?

I’m using L2TP to connect to a remote site. Both computers can connect to the VPN successfully, but they cannot connect to the remote computer. I have used the traceroute to check, and all traffic is routed to the router’s IP.