Unity builds running on Ubuntu 16.04 vs 18.04

Hi,

I'm simulating a physical environment for a drone. The simulation creates a TCP server and waits for a client, a Flight Controller Unit (FCU). Once connected, I send the drone's physical parameters and get back the forces that the drone motors should use for it to fly properly. This happens at 400 Hz and is lock-stepped - one side waits for the other before it sends the next message.
The FCU software we're using is PX4.
The problem is that when the Unity Simulation runs on Ubuntu 16.04, the simulation grays out, locks and responds briefly only once in a while - every 20 seconds or so. When running on Ubuntu 18.04, the connection is fine.
The solution seems simple - upgrade to 18.04. However, we're concerned that since we can't find the actual problem - and we've spent two weeks trying - this might come up again in the future.

Any differences in how Unity calls network operations on the Linux kernel, between 16.04 and 18.04?

Thanks