If I try to use an external Firebird database from other location in the LAN:
I get this:

Even if I can actually access from CLI:
[$] isql-fb
Use CONNECT or CREATE DATABASE to specify a database
SQL> connect '113.128.1.12:/home/asarch/Documentos/Escuela.fdb' user sysdba password masterkey;
Database: '113.128.1.12:/home/asarch/Documentos/Escuela.fdb', User: SYSDBA
SQL>
This is
Version: 25.2.3.2 (X86_64) / LibreOffice Community
Build ID: 520(Build:2)
CPU threads: 4; OS: Linux 6.12; UI render: default; VCL: gtk3
Locale: es-MX (es_MX.UTF-8); UI: es-ES
Debian package version: 4:25.2.3-2
Calc: threaded
Why is that?