U8-11 on a Daikin Altherma: Connection with the Wireless gateway lost

What it means

The manual says: Connection with the Wireless gateway lost.

Part involved: LAN/WLAN adapter / cloud connection.

When it shows: Communication abnormality between unit and wireless gateway.

Is it safe?

The heat pump keeps running.

Resetting itself: yes.

Manual reset: Automatic reset.

What you can check

• Read the full error code and sub-code shown on the user interface (Malfunctioning screen; press the help button for Daikin's long description) and note it, with the date/time, for your installer.
• Check your home router/Wi-Fi is switched on and working and has not been replaced or moved (router changes break the adapter/app link).
• Daikin documents this code as resetting automatically once the condition clears; if it keeps coming back, contact your installer.
• Do NOT bleed radiators while an error/malfunction symbol is displayed: Daikin operation manuals warn refrigerant may have leaked into the water circuit - ventilate and call your installer.

What the engineer will check

• Check that the AP mode is active (= WLAN adapter active as access point). ; | Troubleshooting 2 For more information about the configuration and further troubleshooting, see the ONECTA app or see the website: http:// www.onlinecontroller.daikineurope.com/.

Who to ask for: Installer or homeowner with Daikin app/LAN adapter instructions.

Certification: None.

What you might notice

• App / connectivity problem

What owners and engineers report

7 owner and engineer reports mention this.

• App / connectivity problem on the Altherma: 7 reports

Sources

• Service manual Daikin Altherma 3 M EBLA/EDLA04~08E (ESIE22-09) ↗ · ESIE22-09 · page 77 · Reviewed 23 September 2026

A code explains what the controller detected, not a confirmed root cause.

Reviewed: 23 September 2026