You need to start at the basics how did it tow when you bought it. The main culprit is loading trailer wrong to much tail weight will cause sway. Drain all tanks try not to carry unnecessary stuff etc. When you see Tractor Trailer double or triples or vans heavy front light rear. Plus these rigs brake rear to front and have sliders. Speed is a killer these trailers do not have 22 ply tires and not made to run at high speeds. If my trailers were hooked wrong by someone else and were swaying, just had to take the time to stop and switch safety first. WD bars and sway control are extra measures of safety. Equipment still has to be setup correctly to avoid an accident or worse.
I can tell a hundred examples of pros and cons but it first starts with safety, check tires, hook ups and whatever else do a pretrip and double check when stopped before taking off.