This information might be helpful in your situation if internet access is a necessity.

California has utility power outages, both planned (fire prevention) and unplanned. Our internet is through Comcast cable. Unfortunately, the internet also goes down during power outages, and the most recent outage lasted two days. We have a generator for electricity, but had no easy way to replace the internet.

I have a smartphone that provides a mobile Wi-Fi hotspot, plus an unlimited data plan. This seemed like a logical backup. Laptops can use a hotspot if nearby, but our desktop PC, TV, etc. cannot. They connect by Ethernet cable to our main eero module, which connects by Ethernet cable to the cable modem.

eero Tech Support said the eero main module would not be able to directly use a mobile hotspot to access the internet. I researched the web and found very little advice except one article that concerned a similar situation. It recommended using a wireless Ethernet bridge, not to expand your home's Wi-Fi coverage as an Access Point (which is the typical use), but instead as an Access Point Client to bring the internet in via Wi-Fi and send it out through the Ethernet port.

So I ordered a wireless Ethernet bridge, even though it wasn't clear how it was going to work. Searching Amazon and based on reviews, I chose the TRENDnet TEW-638APB wireless Ethernet bridge (Amazon, $35). You could also use the old router your eero system replaced, but it would require reconfiguration and it may not have the latest security protocols.

After the TRENDnet unit arrived, I followed the instructions.

1. Turn on the smartphone's mobile hotspot, which should be password-protected, and put the phone near the TRENDnet.
2. Unbox and assemble the TRENDnet bridge with the 2 antennas and power cord (supplied). Plug the TRENDnet into an AC outlet.
3. Connect the bridge to the PC with a short Ethernet cable (supplied by TRENDnet).
4. Pop the installation CD-ROM into the PC and run the TRENDnet Setup Wizard software. The setup program will recognize the bridge and lead you through the setup process.
5. ** It's important you select the AP Client configuration, not the default Access Point configuration. **
6. The setup program then connects to your hotspot (you specify the hotspot name from the popup list and enter your password or key). The program confirms the hotspot connection, finishing up the setup process.
7. After completing the TRENDnet setup, I went over to the main eero module and disconnected it from the cable modem, which shut off internet access throughout the house. The TRENDnet bridge, however, was still connected by Ethernet cable to my Ethernet switch, which is downstream from the main eero module, I tried to access the internet --> no luck.
8. Then I moved the TRENDnet bridge (and smartphone hotspot) over to the main eero module and connect the short Ethernet cable from the TRENDnet bridge directly into the main eero module's cable modem Ethernet port.
9. At first, nothing seemed to happen. Then I opened the eero app on my smartphone (even with the hotspot on), and ran an internet speed test from the eero app. This apparently triggered the eero module to look for a new internet source, and it finally found the hotspot. We suddenly had internet throughout the house -- all from the mobile hotspot.

CONNECTIONS

Cable:

• Cable modem --> eero main module --> Ethernet switch --> peripheral eero modules --> end user devices throughout the house

Mobile hotspot:

• Mobile hotspot --> wireless Ethernet bridge --> eero main module --> Ethernet switch --> peripheral eero modules --> end user devices throughout the house

RESULTS

• Cable internet:   368 Mbps download / 12 Mbps upload
• Mobile hotspot:   36 Mbs download (still very usable) / 16 Mbps upload (even better than cable)

The result is easy backup internet access at relatively low cost that gives us peace of mind. Note: it's unlikely cell towers would be part of any planned outage, since mobile communications would be an essential service.