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)

`