my ecobee thermostat is offline in the app every day or two, have to reboot it to get wifi back.

Diagnosis

The intermittent disconnection of the Ecobee Smart Thermostat Enhanced is rarely a failure of the hardware itself, but rather a "handshake" failure between the device's 2.4GHz wireless radio and the router's DHCP lease management. The Ecobee uses a low-power Wi-Fi chip designed for efficiency, not high-bandwidth stability. When a router employs "Smart Connect" or "Band Steering"—which merges 2.4GHz and 5GHz bands into one SSID—the router often attempts to "push" the thermostat to the 5GHz band. Since the Ecobee cannot communicate on 5GHz, the connection drops, and the device enters a dormant state until a hard reboot forces a new DHCP request. Additionally, many modern mesh networks (like Eero or Google Nest WiFi) utilize aggressive "Auto-Optimization" features that rotate channels or prune idle clients. Because the thermostat only sends small bursts of data, the router may flag the connection as inactive and terminate the session. You can confirm this by checking the "Network" menu on the thermostat screen during an outage; if it shows "Connected" but the app says "Offline," the issue is a cloud-sync timeout. If it shows "Disconnected," the issue is a local radio failure caused by signal interference or IP conflicts.

How to Fix It

To permanently stabilize the connection, you must move the thermostat from a dynamic IP environment to a static assignment and isolate the frequency band.

1. Access your router's administrative console by entering the gateway IP (typically 192.168.1.1 or 192.168.0.1) into a web browser.
2. Navigate to the Wireless Settings or Advanced Wi-Fi tab. Locate the "Smart Connect" or "Band Steering" toggle and switch it to OFF.
3. Rename your 2.4GHz and 5GHz bands differently (e.g., "Home_WiFi_2.4" and "Home_WiFi_5"). This prevents the router from attempting to shift the thermostat to the incompatible 5GHz band.
4. Go to the LAN Settings or DHCP Server section. Find the "Address Reservation" or "Static IP" table.
5. Locate the Ecobee in the client list (identified by its MAC address, found on the back of the device or in the Network menu).
6. Assign a specific IP address to the device (e.g., 192.168.1.50) and save the settings. This prevents the "IP lease expired" crashes that necessitate reboots.
7. On the Ecobee thermostat, go to Main Menu > Settings > Wi-Fi, select "Forget Network," and reconnect to the newly renamed 2.4GHz-only SSID.

If That Didn't Work

• Disable AP Isolation: Ensure "AP Isolation," "Client Isolation," or "Guest Mode" is disabled in your router settings. If enabled, the router prevents the thermostat from communicating with other local devices and the gateway, leading to intermittent cloud timeouts.
• Change the Wi-Fi Channel: Use a Wi-Fi analyzer app to find the least congested channel on the 2.4GHz spectrum. Manually set your router to Channel 1, 6, or 11 rather than "Auto." This eliminates interference from neighboring routers that causes the Ecobee's modest radio to drop the signal.
• Install a C-Wire Adapter: If you are using the Power Extender Kit (PEK) instead of a dedicated C-wire, the thermostat may be experiencing "power brownouts" during high-load cycles (like when the screen is bright or the radio is searching for signal). Install a 24V C-wire transformer to ensure the Wi-Fi chip has a constant, ripple-free power supply.
• Adjust Firewall/DNS Settings: Change your router's DNS providers to Google DNS (8.8.8.8 and 8.8.4.4) or Cloudflare (1.1.1.1). Ecobee servers occasionally struggle with ISP-provided DNS, causing the app to report the device as offline even when the local Wi-Fi connection is active.

Heads Up

• Avoid placing large metal objects or mirrors directly between the router and the thermostat, as the 2.4GHz signal is highly susceptible to reflection and attenuation.
• If you use a Mesh system, try placing a node within 15-20 feet of the thermostat to ensure a signal strength of at least -65dBm.
• Never use "WPA3-only" security mode; the Ecobee Enhanced works most reliably with WPA2-AES (CCMP) encryption.
• Regularly check for firmware updates in the Ecobee app, as they often include patches for the wireless driver's reconnection logic.