My washing machine drain line has been overflowing a lot lately. I try liquid fire and running a water hose down it to unclog it. I've even ran a snake down it and got dirt and a little rust on it. What does this means? What's a good way to unclog it.

How old is your house and what are the pipes made of? I would snake out the washer drain from the washer roof vent. Put out enough cable to get to the base and 20 feet more. Good luck, Tom