What is the best way to stop snoring at night when sleeping hard?

Sleep sideways. Snoring can be a sign of sleep apnea. May want to have a sleep study performed. Your family md can order a sleep study and one can be performed at a sleep center. Consult and ENT and an oral surgeon afterwards for surgical options, CPAP and an oral appliance.
Need to be seen. You should be seen by a sleep specialist for a thorough evaluation of your sleep. This can be an ENT (otolaryngologist), a neurologist, or a pulmonologist. In the meantime, you should not sleep flat on your back, but on your side or stomach, and side sleeping with some elevation is quite helpful.