Connect client to server in different subnets

Hello,
I want to connect my UrBackup server (10.40.4.10) to a client located in a different subnet (10.40.8.55). Neither machine has internet access.
Do the server only uses broadcast to find clients, which doesn’t work across subnets.
Is it possible to connect them without internet? How can I configure the server or client so they communicate across subnets?
Thanks for your help!

As long as the clients have static addresses, you can press the blue “add client” button on the server web interface, and enter the IP addresses (one at a time) into the “local/different subnet” box.

Thank you for the reply. But even if I add a new client, the server still can’t find it. I even tried moving the client to the same LAN as the server and disable every firewall rules. Maybe my client and server versions aren’t compatible — I don’t know.

server : wget https://hndl.urbackup.org/Server/2.5.33/urbackup-server_2.5.33_amd64.deb
sudo dpkg -i urbackup-server_2.5.33_amd64.deb

client : TF=$(mktemp) && wget “https://hndl.urbackup.org/Client/2.5.25/UrBackup%20Client%20Linux%202.5.25.sh” -O $TF && sudo sh $TF; rm -f $TF

Found the solution guys, i didnt specify the server IP in the client configuration file