How can I evaluate the stability of a connexion between two computers on the same network ?
You could run test traffic (with at least 50% of the connection's bandwidth) and analyze loss, e.g. using iperf3.
What are your advices to improve stability ? Other mean of connection ? Better ethernet cable ? More powerful router ?
Generally, shielded cable (S/FTP)...
If feasible, optical fiber is immune to interference.
You can use small industrial-grade switches with SFP port (to connect the fiber) in the machine.
However fiber is much more fragile then copper and you must pay attention to the bending radius.
The speed of light and the speed of the electromagnetic waves all travel at the speed of light in a vacuum. In cable, all of these waves travel at about 67 to 95% of the speed of light. If I could send something down some type of cable at twice the speed of light it would not make any difference to network speed because the rate at which data is sent is much ...