lost connection to my bcc100 on the app, now it says 'offline' and won't rediscover.

Diagnosis

The "Offline" status on a Bosch BCC100 usually indicates a synchronization failure between the thermostat's onboard Wi-Fi module and the local network gateway. This typically happens when the device loses its DHCP IP lease from the router or encounters a "zombie" connection where the hardware believes it is connected to the SSID, but the handshake with the Bosch cloud server has timed out. In many cases, this is triggered by a brief power flicker or a router channel hop (switching from 2.4GHz to 5GHz), which causes the BCC100 to hang in a reconnection loop. You can confirm this by checking the thermostat screen; if the Wi-Fi icon is blinking or missing entirely while your other home devices are online, the communication stack has crashed and requires a hard signal refresh to re-authenticate with the server.

How to Fix It

To restore the connection without wiping your custom temperature schedules or setpoints, follow this precise sequence to reboot the wireless interface:

1. Navigate to the physical BCC100 wall unit. Ensure the screen is awake.
2. Press and hold the center OK button firmly for exactly 10 seconds. You will see the screen flash or the backlight flicker; this indicates the Wi-Fi module is performing a soft reboot.
3. Wait 60 seconds for the device to attempt a handshake with your router. Look for the Wi-Fi icon to turn solid on the display.
4. Open the Bosch Home Comfort app on your smartphone.
5. On the main dashboard, perform a "pull-to-refresh" gesture (swipe down from the top of the screen) to force the app to poll the cloud server for the device's updated status.
6. If the device remains offline, toggle your phone's Wi-Fi off and back on to ensure the app is not caching a stale local network state.

If That Didn't Work

If the soft reset fails, try these more aggressive recovery methods:

• Power Cycle the HVAC Transformer: Locate your home's electrical panel and flip the breaker for the HVAC system (Furnace/Air Handler) off for 30 seconds. This completely drains the capacitors in the BCC100 and forces a cold boot of the network card, which often clears stubborn IP conflicts.
• Static IP Assignment: Access your router's admin panel (usually 192.168.1.1) and locate the MAC address of the BCC100. Assign a "DHCP Reservation" or Static IP to the device. This prevents the "Offline" error from recurring when the router rotates IP addresses every few days.
• 2.4GHz Band Isolation: The BCC100 cannot communicate on 5GHz bands. If you have a dual-band router with "Smart Steering" (one SSID for both bands), the thermostat may be trying to connect to the 5GHz signal. Create a separate Guest Network specifically for 2.4GHz and reconnect the thermostat to that dedicated SSID.
• Factory Network Reset: If all else fails, enter the Setup menu on the device, select 'Network', and choose 'Reset'. You will need to re-enter your Wi-Fi password and re-pair the device to the app as if it were a new installation.

Heads Up

• Signal Strength: Ensure there are no large metal objects or mirrors directly between the BCC100 and your router, as these cause signal attenuation that leads to intermittent "Offline" drops.
• Firmware Updates: When the device comes back online, check the app for any pending firmware updates. Bosch frequently releases patches to improve the stability of the Wi-Fi handshake.
• Router Compatibility: Avoid using WPA3 security settings; the BCC100 is most stable using WPA2-AES encryption.