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It's been a crazy couple of months recently. With what began as a temporary lockdown & mandatory work-from-home has now become a question of "Will we ever return to the office"?

Luckily I have a decent home office setup, as my job is already primarily work from home. That being said - it's more important than ever to have a stable, reliable internet connection available. Can't run the risk of being in an important meeting with a customer and drop from the video conference (or have audio issues, etc).

Needless to say, my internet provider is far from perfect. While it does perform reasonably well most days, the spikes in latency & packet loss have increased substantially with everyone in the neighborhood working from home.

I've been debating for a while on whether or not to pick up a cellular modem. Originally I had planned on having one handy for a complete internet outage (which happens). But more recently I began to wonder if it might be worth it for routing around my primary provider when the connectivity is poor.

To accomplish this, I decided to use Google Fi. I've already used the service as my cellular provider for a number of years now and I've been extremely pleased with the service. One of the awesome benefits they offer for subscribers is free data-only SIM cards. So I could pay nothing for the SIM card itself (no plan/recurring costs either) - then only pay for data as I use it.

First, I went ahead and tested what typical latency & performance was over my cell connection. Occasionally my home internet provider would see latency spikes up to 1200-1800ms. Checking the cell connection - it seemed pretty stable in the 200-300ms range. Still pretty high, but much more bearable than ~1200ms. Seemed like it should work reasonably well for what I wanted.

Then, I had to double check compatability. Google Fi runs over multiple carriers on the backend - as long as you're using a Fi-compatible device. If not, it seems they default to only using T-Mobile's network. So in that case, Fi requires that our device supports LTE bands 2 & 4 at a minimum. The Netgear LB1120/1121 modems do, so we're good there.

Next, I went ahead and ordered a NetGear LB1121 LTE Cellular modem. I opted for the power over ethernet model, since I already had a Cat5 run over to where the modem would be placed. The switch I'm using is also being backed up by a UPS, so in the event of a power outage the LTE modem would stay online.

Finally - I placed my order for the Google Fi SIM card. Easy process - $0 for the SIM, $0 for shipping, and it arrived in only a few days. As an additional note - the modem requires a micro-SIM, but Fi provides nano-SIM cards. I also had to pick up a cheap adapter kit to make this work.

Getting the Modem Set up

Once the modem & SIM card arrive, it's time to get started. This will be a fairly quick and straightforward process.

On the bottom of the LTE modem, the device will list it's default IP address & the password to log in. Take note of that, as you'll need it later.

Also on the bottom is the slot to insert the SIM card. Remove the cover, insert your SIM card into the micro-SIM adapter, then insert into the cellular modem.

Next, go ahead and power on the modem & get it plugged into a PC.

Once the modem boots up - we should be able to reach it via a web browser @ 192.168.5.1.

Log in with the credentials from the bottom of the modem.

Upon landing on the main page, you may see that the modem auto-connects to T-Mobile's network. While we might be able to use this as-is, ideally we need to change our connection to specifically use Google Fi's information.

Head over to Settings > General > APN:

Click Add to create a new cellular profile

For the network Name, enter Google Fi. For the APN enter h2g2.

Click Save to add the profile

Then make sure to select the correct radio button to activate the new profile:

At this point, I would recommend deleting the old/default T-Mobile profile. I would also suggest rebooting the device to force it to switch to Google Fi.

If all is well - You'll log back in and see that the modem has now connected to the appropriate network:

Note: I've had some issues where the carrier name doesn't display correctly. It may take a few minutes to finally display "Google Fi". However, at this point you should be connected to the correct network and be able to use it with no issues

Additional Settings

One other thing that may be worth noting. Depending on how you're using the modem, you may want to change the way the modem operates.

Let's go ahead and check out a few options on the LAN settings page. This can be found by going to Settings > Advanced > LAN.

By default, the modem operates in router mode. What this means is that the modem terminates the connection from Google Fi - and acts as a gateway between your devices & the carrier network.

You would want to use router mode if you have multiple devices you want to use with the modem & you do not have an additional router or firewall. In this case, the modem will handle providing IP addresses to the client devices. In addition, it will act as a firewall and allow client devices to the internet, while blocking any external devices from accessing the clients directly.

The other available mode is bridge mode. In this case, the modem operates as a pass-through device & assumes that there is another device behind the modem that is providing the routing/firewalling functionality.

You may want to use bridge mode if you already have a router or firewall you want to use - and you want to treat the modem as a second internet connection. When the modem connects to the provider, it will automatically pass the public IP address & configuration straight through to whatever device is plugged into it.

If you're interested in how I configured the auto-failover to the cellular modem - check back in a bit. I wrote some custom automation to monitor my primary connection & conditionally inject a route over the LTE modem.

I'm just wrapping up some of that, and should have something posted here shortly!