An access point link is up, and the switch port is hardcoded to half duplex while the access point is set to negotiate. The port shows collisions and late collisions. Clients are slow only when they pass traffic. What is mismatched?

A duplex mismatch puts one side in half and the other in full, and the result is collisions and late collisions on a link that still shows up. This switch port is hardcoded to half and the access point is negotiating, which is the mismatch. Clients feel it when they pass traffic, not when they merely associate. The country code does not create collisions. A VLAN mismatch fails addressing or reachability. It does not late-collide on the wire. The beacon interval does not select duplex. The switch port is hardcoded to half duplex and the access point is negotiating full. The link is up and full of errors. Check one live client after the change and leave the rest of the floor alone until that client matches the result you expected. Confirm the symptom on the next attempt before changing anything else. Exam caveat: locking both ends to full is fine, and locking both to half is slow but consistent. The failure is the disagreement. Operational check: set both ends to negotiate, or set both to the same duplex, and confirm the collision counter stops climbing.