The Belkin firmware requires: 1. A hidden __templates__ field in all form POSTs 2. Image button actions submitted as name.x=0&name.y=0 (not name=value) 3. ECG_kvm_powerport_cnt hidden field Without these, the device returns "Permission denied" on port config saves. Also fixed the switch endpoint with the same pattern. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>