Are you sure it's network lag?
I'm asking because I'm also experiencing lag, but in my case it strangely seems to be caused by the CPU. But it's not that my processor was to weak or anything, because the lag appears quite randomly and maps which are perfectly playable most of the time are sometimes a stuttery mess. (Bug report:
https://answers.ea.com/t5/Bug-Reports/Random-CPU-lag/m-p/6441424)
Have you already looked at the in-game fps counter? It also shows lag spikes caused by the CPU. You can enable it by pressing the ^ key, typing "perfoverlay.drawfps 1" and hitting enter.
Also you can use "networkperfoverlay.enable 1" to monitor your network performance (didn't try this one in Battlefront 2 yet, but since it's the Frostbite Engine I guess it should work).
