I have 3 floor drains in my basement that are clogged.I have ran commercial auger down
The main sewer line twice.I have snaked the vent tube but hit something that I can't get through, should I be abke to run this freely to the main sewer line.toilets are not affected by the clog. Thanks

You should be able to run a snake down from a vent and into a drain line unobstructed. Sounds like something is clogging the drain line as you suspected. Snake the vent and then pull the snake back WITHOUT pushing back into snake drum... and measure distance that you felt blockage... transfer that measure to pipe and try to see where the snake ended inside house... see from there.

OK, so your blockage is not in the main sewer line. It must be in the pipes of the floor drains. May be in the trap. Try plunging. Getting a snake through a 2" trap is pretty hard. Anything smaller is almost impossible. You might try a closet auger but probably won't be successful. Try a sticking wire coat hanger to stir things up. Then plunge. Try a cup of bleach or boiling water to soften things, then plunge. There is also a gaget, don't remember what its called but it's a rubber diapharn the fits on the end of a garden hose. The water pressure from the hose is supposed to expand the diaphram and seal the pipe then water is forced under pressure through the pipe. I have a couple of them but have never used. Seems like it should work if blockage is before first vent.

I have tried all of the ideas you suggested nothing works. Thanks

Is it possible that your floor drains may be pipe to daylight or to the foundation drain. I have hear that some municipalities don't allow floor drains to the sewer line.

I'm in the country in septic system. Thanks

Harold is right about floor drains don't always go into the sewer or septic. Do you have a sump pump? Floor drains in my area go to the sump only. How are you testing these drains to see if they are plugged?

When I put a waterhose down my vent tube from roof I have water running out of upstairs bathroom. Thanks

This means you have a plugged drain above the first fllor connection from the second floor.

How do I go about fixing this.and why does this not affect my toilets.only backs up on the floor darins in basement. Thanks