Split screen lag/timing issues

Me and my friend tried playing it takes two and for the first few hours it was fine but one day we loaded it up and it was really laggy. As in I would be moving fine on my screen but my friend would stay in one place and when they did it would be really stuttery. I've tried reinstalling the game, turning all the graphics options to low, and everything else I can think of but it just doesn't work. This issue only affects me. We're currently on the octopus fight but the boat on both our screens is out of sync. Does anyone know how to fix this problem? We can't do local as we don't live together and both our computers are connected to ethernet. These issues started during the queen wasp fight.