socket communication issue

[J4S0N-H]

I'm basing a project on this repo's use of multicontainers. I thought it would be nice to try socket communications between my docker containers. I can make the connection successfully, and even send data from the client to the server on port 80. When I try to send data from the server back to the client (port 8181), the data never gets there. I've played with the ports in my docker-compose.yml file. Maybe I'm overlooking something obvious?

` version: '2' services: frontend: build: frontend network_mode: host privileged: true ports: - "80:80" packet_radio: build: packet_radio network_mode: host privileged: true labels: io.balena.features.kernel-modules: 1 io.balena.features.firmware: 1 ports: - "8181:8181" browser: image: balenablocks/browser privileged: true network_mode: host ports: - '5011' # management API (optional) - '35173' # Chromium debugging port (optional)

`