I recently had a plumber add a vent to my toilet. He installed new vent outside of the house directly into the large drain line. This is past my kitchen sink, toilet, bathroom sink and shower. I am still having what seems like clogging problems. Advice on how to properly vent would be appreciated. I have already ran power snake through the system and found no clogs.

My system is as follows: kitchen sink drains to batroom sink drain then shower returns to batroom sink drain. The toilet is after the kitchen sink.

Kitchen sink_____________Toilet____________Bathroom sink_________Shower Thaks for any help, dsmedley