If you access your internal server not with ip but with a simbolic name you can set simbolic name associated with internal ip in dns.
example internal server 192.168.0.100 you can create a A record with myserver 192.168.0.100
Now if use simbolic name in broser you are connected to 192.168.0.100.
Also commercial router have this problem. For example zyxel.
Bye.