I have a leak coming from the drain in a toilet. I have already replaced the wax ring twice to no avial. The water only leaks when a connecting toilet is flushed. The drain pipe connects two bathrooms but the water only leaks from the 2nd toilet when the 1st toilet is flushed. It does not leak when the 2nd toilet is flushed. It seems to be leaking from directly under the 2nd toilet. Any suggestions?

It sounds like you have a clog that's backing up into the 2nd. Toilet. Wax rings seal off the discharge and odor but are not designed to hold standing water such as a back up. You may ask why one toilet and not both. I can't answer that. Perhaps the wacx seal on toilet #1 is making a better seal, I don't know, but one thing's clear. You need to have the drain line snaked and possibly the 2nd toilet set with a new wax ring. Good luck, Tom

I agree with that answer