Undisciplined Classroom

I teach chemistry in a community college and I have the most undisciplined classroom I’ve ever had. Students are half doing the work they’re supposed to do but mostly chatting, texting each other when I’m talking, late to come to class, late to come back from break. I’m known to be a good teacher but they don’t seem to appreciate it at all. They snicker when I talk, give each other looks when I ask questions to the classroom, I think they might be texting each other while I talk, just general lack of appreciation of what I can say after 15 years is a legitimately good classroom experience. I flipped like classroom and my structure relies on the students following the guidelines of the classroom but the half-ass following is not helping the struggling students. It’s kind of a mess.

Today I gave a big speech about behavior and how I won’t write a recommendation for students that don’t follow certain parameters and they still came back late from break. Any advice?