So I have configured my ubuntu server to be router with dhcp functionalities and I want it to appear on other computers or devices as a choice for a network connection. My ubuntu router is currently connected to a wireless router which provides internet but I want it in a such a way that the ubuntu router is among the list of network connections to be chosen from. How do I do this?
Plug the output of the Ubuntu box into the input of the wireless router.
Consider the wireless router's broadcasted network a broadcast of the Ubuntu box as any connections made to that network will be served by the Ubuntu computer.
Also, many wireless routers offer the option of either serving DHCP within the network or having DHCP handled outside the router itself so if you have this option, you will have the option to allow the Ubuntu box to serve DHCP as well.