I have a lab with Windows Server 2008 R2 acting as a domain controller for domain win.testlab with IP address 10.0.1.1. I have several Windows Server 2012 VMs connecting to this domain within the same subnet with no problems. Windows Firewall is off. The network is 10.0.1.0/24.
I have a Windows Server 2012 machine on network 10.0.2.0/24 called LIME with IP address 10.0.2.2 and I want to join it the win.testlab domain. I can ping the domain controller with no issues and when I run net view \\10.0.1.1 I get a reponse back showing me the shares on the DC. All looks good.
Now, when I try and join the domain using the NETBIOS name of WIN it fails, but if I join with win.testlab it succeeds. Does that indicate something up with the router between the subnets? Do you know what? It's not causing any issues but it leads me to suspect a misconfiguration of the router.
NetBIOS relies on broadcast name resolution. Routers don't generally forward broadcast traffic. I would expect this behavior in this scenario so I don't believe there's a problem with the router and what you're experiencing sounds perfectly normal.