Executing the client I get : client connect failed. connection request timed out

[raphael10-collab]

I've put the server code in a Cloud VPS with IP Address: aaa.aaa.a.aaa :

(base) root@WorldMap:~/netcodeServer# cat CMakeLists.txt 
cmake_minimum_required(VERSION 3.15...3.31)
project(NetCodeServer)

include(CMakePrintHelpers)


set(CMAKE_CXX_STANDARD 20)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

include(FetchContent)

# https://github.com/robinlinden/libsodium-cmake?tab=readme-ov-file#using-in-your-project
# https://www.tldrlegal.com/license/isc-license
FetchContent_Declare(Sodium
    GIT_REPOSITORY https://github.com/robinlinden/libsodium-cmake.git
    GIT_TAG e5b985ad0dd235d8c4307ea3a385b45e76c74c6a # HEAD, last updated at 2025-04-13
)
set(SODIUM_DISABLE_TESTS ON)
FetchContent_MakeAvailable(Sodium)

add_executable(${PROJECT_NAME}
    src/netcode/netcode.c
    src/server.c
)

target_include_directories(${PROJECT_NAME} PUBLIC
    src/netcode/include
)

target_link_libraries (${PROJECT_NAME} PUBLIC
    sodium
)

Server side code :

(base) root@WorldMap:~/netcodeServer/src# ls -lah
total 20K
drwxr-xr-x 3 root root 4.0K Jun  5 18:27 .
drwxr-xr-x 4 root root 4.0K Jun  5 18:27 ..
drwxr-xr-x 3 root root 4.0K Jun  5 15:35 netcode
-rw-r--r-- 1 root root 4.6K Jun  5 18:27 server.c

where server.c is taken from here: https://github.com/mas-bandwidth/netcode/blob/main/server.c while netcode.h and netcode.c :

(base) root@WorldMap:~/netcodeServer/src/netcode# ls -lah
total 332K
drwxr-xr-x 3 root root 4.0K Jun  5 15:35 .
drwxr-xr-x 3 root root 4.0K Jun  5 18:27 ..
drwxr-xr-x 2 root root 4.0K Jun  5 15:10 include
-rw-r--r-- 1 root root 320K Jun  5 15:35 netcode.c
(base) root@WorldMap:~/netcodeServer/src/netcode# cd include/
(base) root@WorldMap:~/netcodeServer/src/netcode/include# ls -lah
total 24K
drwxr-xr-x 2 root root 4.0K Jun  5 15:10 .
drwxr-xr-x 3 root root 4.0K Jun  5 15:35 ..
-rw-r--r-- 1 root root  13K Jun  5 15:10 netcode.h

are taken respectively taken from: netcode.h : https://github.com/mas-bandwidth/netcode/blob/main/netcode.h netcode.c : https://github.com/mas-bandwidth/netcode/blob/main/netcode.c

Client side :

(base) raphy@raohy:~/netcodeClient$ cat CMakeLists.txt 
cmake_minimum_required(VERSION 3.15...3.31)
project(NetCodeClient)

include(CMakePrintHelpers)


set(CMAKE_CXX_STANDARD 20)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

include(FetchContent)

# https://github.com/robinlinden/libsodium-cmake?tab=readme-ov-file#using-in-your-project
# https://www.tldrlegal.com/license/isc-license
FetchContent_Declare(Sodium
    GIT_REPOSITORY https://github.com/robinlinden/libsodium-cmake.git
    GIT_TAG e5b985ad0dd235d8c4307ea3a385b45e76c74c6a # HEAD, last updated at 2025-04-13
)
set(SODIUM_DISABLE_TESTS ON)
FetchContent_MakeAvailable(Sodium)

add_executable(${PROJECT_NAME}
    src/netcode/netcode.c
    src/client.c
)

target_include_directories(${PROJECT_NAME} PUBLIC
    src/netcode/include
)

target_link_libraries (${PROJECT_NAME} PUBLIC
    sodium
)


(base) raphy@raohy:~/netcodeClient/src$ ls -lah
total 20K
drwxrwxr-x 3 raphy raphy 4,0K giu  5 18:25 .
drwxrwxr-x 4 raphy raphy 4,0K giu  5 18:28 ..
-rw-rw-r-- 1 raphy raphy 5,0K giu  5 18:19 client.c
drwxrwxr-x 3 raphy raphy 4,0K giu  5 18:17 netcode

(base) raphy@raohy:~/netcodeClient/src$ ls -lah ./netcode/
total 332K
drwxrwxr-x 3 raphy raphy 4,0K giu  5 18:17 .
drwxrwxr-x 3 raphy raphy 4,0K giu  5 18:25 ..
drwxrwxr-x 2 raphy raphy 4,0K giu  5 18:17 include
-rw-rw-r-- 1 raphy raphy 320K giu  5 18:17 netcode.c

client.c : https://github.com/mas-bandwidth/netcode/blob/main/client.c

where:

NETCODE_CONST char * server_address = "aaa.aaa.a.aaa:40000";

netcode.h : https://github.com/mas-bandwidth/netcode/blob/main/netcode.h netcode.c : https://github.com/mas-bandwidth/netcode/blob/main/netcode.c

Building and executing the Server :

[100%] Built target NetCodeServer
(base) root@WorldMap:~/netcodeServer# ./builddir/NetCodeServer 
[server]
server listening on aaa.aaa.a.aaa:40000 
server started with 256 client slots

Building and executing the Client I get `client connect failed. connection request timed out :

(base) raphy@raohy:~/netcodeClient$ ./builddir/NetCodeClient 
[client]
client started on port 55685
client id is f09c63de9897b8a4
client connecting to server aaa.aaa.a.aaa:40000
client connect failed. connection request timed out
client disconnected

OS: Ubuntu 24.04 gcc (Ubuntu 13.3.0-6ubuntu2~24.04) 13.3.0

What am I doing wrong and/or missing? How to make it work?