Duplex Mismatch

Information & Communication Dictionary
A failure mode arising when two communicating devices are configured for incompatible duplex modes (for example, one for frequency-division duplexing (FDD) and the other for time-division duplexing (TDD), or one set to half‑duplex while the peer expects full‑duplex), preventing correct bidirectional exchange of signals or causing collisions and loss of synchronization.