I use the docker container provided by:

steefdebruijn/docker-roonserver

Haven't had an issue yet. But this is running on Ubuntu. Also verify your firewall rules are allowing inbound connections on the correct ports.

Do you have multiple VLANs? Do you have a firewall enabled on the machine? If your laptop and phone are in the same subnet and VLAN (hopefully, if not something is very wrong) then the server and client poth broadcast on a specific port (can't remember right now). They should see this. If not you've got a firewall problem. That's my best guess.