I work for a private employer. The boss said it was against company policy to discuss politics or religion with customers. Does that violate my freedom of speech?
No, the First Amendment does not limit private employers. The Bill of Rights — and the First Amendment — limit only government actors, not private actors. This means that private employers can restrict employee speech in the workplace without running afoul of the First Amendment. Private employees would have to rely on other sources of law (e.g., contract law, tort law or state employment statutes) to seek relief in court.
Public employers also can set rules for employee behavior in the workplace. However, public employers are government actors and are subject to the limitations of the Bill of Rights, including the First Amendment.