Shelly 2 Automatically turns ON/OFF relay 2 with external switch connected · Issue #4665 · arendst/Tasmota · GitHub
Shelly support group (English Version), Does anyone know how to wire a Shelly Dimmer 2 to 3-way switches
Shelly 2 Automatically turns ON/OFF with external switch connected · Issue #3896 · arendst/Tasmota · GitHub