How to access the server from an external device while being on the same network as the server?

Question

ubuntu

In general, I installed the Ubuntu server, forwarded the ports on the router.
Because the server is on an old PC and I'm sitting from a laptop, I'm connected to the same Wi-Fi router as the server
I sewed the site, the site opens perfectly from another network (from a phone for example) to open it on my laptop you need to change the IP , otherwise it does not fit on the outside. although I get into VESTA via local IP 192.168.0.103, enter an external timeout, change the IP on the laptop and calmly connect to the external one.
Also FTP issues: Data connection could not be established: WSAEADDRNOTAVAIL - Unable to assign the requested address
All ports are forwarded. And everyone is pinged by external sites. like 2ip for example.

Answer 1

look aside double naton the router Is
n't it easier to register a dns server name at the local address?

Answer 2

Really registered DNS and all the rules.
But FTP won't connect either.

Answer 3

If you need to access the same service under the same domain name, isn't it easier using DNS or simply by writing to hosts to assign the internal address of the same service to the domain name?
In such cases, I myself use address rewriting through hosts and don’t worry too much.