Thermostat shows E20 and cannot control smart radiator thermostats (TRVs) in the same room.

Safety first: Battery TRVs are low risk; isolate mains before handling HubR.

• Check room assignments: In the Wiser app, verify that the thermostat and TRVs are assigned to the same room and controller.
• Rebind devices: Remove the TRVs from the room, reset them (following Drayton instructions), then re-add and bind them to the thermostat’s room.
• Update firmware: Ensure all TRVs and the HubR are on the latest firmware via the app.
• Factory reset if needed: If E20 persists, reset the thermostat’s room configuration and rebuild the room from scratch in the app.